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\title{Integrating telomere biology into the ecology and evolution of natural
populations: progress and prospects}



\author[1]{Pat Monaghan}%
\author[2]{Mats Olsson}%
\author[3]{David Richardson}%
\author[4]{Simon Verhulst}%
\author[5]{Sean Rogers}%
\affil[1]{Glasgow University}%
\affil[2]{Goteborgs Universitet}%
\affil[3]{University of East Anglia}%
\affil[4]{University of Groningen}%
\affil[5]{University of Calgary}%


\vspace{-1em}



  
  \date{June 17, 2024}


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\textbf{Integrating telomere biology into the ecology and evolution of
natural populations: progress and prospects}

Monaghan, Pat\textsuperscript{1}; Olsson, Mats\textsuperscript{2};
Richardson, David S.\textsuperscript{3}; Verhulst,
Simon\textsuperscript{4}; and Rogers, Sean M.\textsuperscript{5,6,*}

1. Institute of Biodiversity, Animal Health and Comparative Medicine,
College of Medical, Veterinary and Life Sciences, University of Glasgow
Glasgow, G12 8QQ, UK.

2. Department of BioEnv -- Zoologen, University of Gothenburg, Sweden

3. School of Biological Sciences, University of East Anglia, Norwich
Research Park, Norwich, Norfolk NR4 7TJ, UK

4. Groningen Institute for Evolutionary Life Sciences, University of
Groningen, Groningen, The Netherlands.

5. Department of Biological Sciences, University of Calgary, Calgary,
Canada

6. Bamfield Marine Sciences Centre, Bamfield, Canada

* corresponding author

Orcid Id:

Simon Verhulst: 0000-0002-1143-686

Pat Monaghan: 0000-0003-2430-0326

Mats Olssen; 0000-0002-4130-1323

Sean M Rogers; 0000-0003-0851-8050

David S Richardson: 0000-0001-7226-9074

Telomeres are fascinating stretches of protective DNA that cap the
chromosome ends of eukaryotes. Without telomeres, during cell division
and DNA replication, DNA repair proteins would misread the ends of
chromosomes and attempt to repair or remove this region of the genome,
leading to instability. Furthermore, the loss of DNA that inevitably
occurs during cell replication due to the end replication problem and
oxidative damage would erode the coding sequences of chromosomes,
eventually causing genome malfunction. Telomeres protect the chromosome,
but in the absence of restoration, some reduction in telomere length
will occur with each cell division, eventually giving rise to cell
replicative senescence often followed by cell death. Short and/or
dysfunctional telomeres underly many disease states and are associated
with ageing. Consequently, telomere biology is a vibrant area of
biomedical research. However, until relatively recently, most of the
research on telomeres has been focused on humans or animal models. That
the basic pattern of progressive telomere loss and little restoration in
most somatic tissues, as found in humans, might not apply to all
eukaryotes had received relatively little attention. In fact, any
variation in the expected pattern of decline in chromosomal telomere
length with progressive rounds of cell replication, as observed in most
human tissues, was initially attributed to methodological issues.
Importantly, the science of studying telomeres has now expanded to
encompass non-model organisms. Variation in the pattern of telomere loss
and restoration across a range of species promises to reveal great
insights into the drivers of life-history trade-offs and evolution,
population ecology and consequences of exposure to environmental stress
in natural populations.

The burgeoning interest in telomere dynamics in non-model organisms and
increased communication between biomedical researchers and evolutionary
ecologists is now enriching our understanding of the diversity of
telomere dynamics. While the basics of telomere biology appear to be
conserved across the eukaryotes, and the range of species studied is
still phylogenetically restricted, differences in detail are
increasingly being revealed (Monaghan et al. 2018). We now have
information on how the pattern of telomere change can vary among species
and include lengthening as well as shortening across the life course
(Remot et al 202x, Brown et al. 2022). Our understanding of how these
patterns relate to environmental factors, species, individual histories
and population process is increasing. Furthermore, telomere biology has
the potential to be used in conservation biology, providing information
about individual and population health (e.g. Eastwood et al. 2022). The
molecular ecology of telomeres in non-model organisms will have greater
impact as discoveries will increase our understanding of the genomics,
ecology and evolution underlying telomere diversity. This special issue
brings together a collection of papers that illustrate the breadth of
taxa now being investigated and ways in which emerging hypotheses,
formed from the perspectives of ecology, evolution and conservation, are
being tested. In this introduction, we highlight how this body of work,
including new information and insights, points the way to many research
questions that remain to be investigated in this emerging,
cross-disciplinary area of biology.

Ecological and environmental stressors

Exposure to stressful environments can have long lasting effects on
health and longevity, and some of these effects are linked to changes in
telomere dynamics. In addition to furthering our understanding of the
mechanism underlying these adverse effects, the study of telomere
dynamics in relation to environmental conditions offers the potential to
measure the scale and extent of their impact at individual and
population levels (K\selectlanguage{ngerman}ärkkäinen et al 202xa), evaluate environmental
quality and examine the effect of conservation measures, such as habitat
restoration. In this special issue, Brown et al. 2021 report apparent
telomere lengthening in both sexes associated with increased survival in
a small passerine bird, the Seychelles warbler \emph{Acrocephalus
sechellensis} . However, sex-specific effects of stressors influenced
the patterns of telomere change. In females, stress induced by low food
availability and malarial infection was associated with the expected
telomere shortening, but there were no such effects in males. Moreover,
less exposure to such stresses appeared to lead to telomere lengthening
(Brown et al 2021). Reichard et al. (2021) also report intraspecific
variation in the outcome of stress exposure using African killifish.
This involves strains derived from wild populations
of\emph{Nothobranchius furzeri} and its sister species, \emph{N.
kadleci} , from sites along a strong gradient of aridity, which
ultimately determines maximum natural lifespan in these species.
Interestingly, they demonstrate that individual condition and
environmentally-driven selection can modulate the relationship between
telomere length and lifespan in opposite directions, validating the
existence of inverse trends within a single taxon and again highlighting
the importance of sex-specific effects. Altogether, the apparent
association between telomere lengthening and stress exposure (see below
for further examples) and among individual differences in telomere
dynamics, for example in relation to age, sex or individual history,
require further investigation. Such studies need to use accurate and
repeatable within-individual measurements where possible and bear in
mind the need to take measurement error into account (Steenstrup et al.
2013).

Intrinsic and extrinsic stress exposures in early life are known to have
substantial and long-lasting effects on phenotypic development.
Conditions experienced inside the cell or from the external environment
during growth can influence telomere dynamics, as shown in this special
issue. In European badgers \emph{Meles meles} , van Lieshout et al.
(2021) report that cubs born in warmer, wetter springs have longer
telomere lengths, which is in turn linked to survival. In purple-crowned
fairy wrens (\emph{Malurus coronatus} ) the rate of telomere shortening
in the first year of life predicted lifespan (Sheldon et al 2021b). More
broadly, it has been hypothesized that measuring the effects of adverse
environmental conditions induced by anthropogenic stressors (such as
chemical pollutants, noise and inappropriate light) on telomere dynamics
could assist in the monitoring and conservation of wildlife. In this
context telomere measurements have the potential advantage over many
other biomarkers of representing a potential fitness proxy, allowing
effects to be studied over a time scale that could be much shorter than
required to measure actual fitness consequences. In line with this,
Salmón and Burraco (2022) evaluated the use of changes in telomere
dynamics as a way of assessing such anthropogenic impacts, providing an
exhaustive literature review and meta-analysis. Oxidative stress induced
by internal and external factors can be a major cause of DNA damage
which could increase telomere attrition. Metcalfe and Olsson (2021)
provide a compelling case that endogenous reactive oxygen species
produced in the mitochondria create links between mitochondrial
function, DNA integrity and telomere dynamics. They argue that telomere
dynamics are best understood when considering the optimal solution to
the trade-off between energetic efficiency and chromosomal protection
that will differ among individuals and change over time, depending on
resource availability, energetic demands and life history strategy. Such
inferences may cumulatively help explain why the effects of stressors on
telomere dynamics are evident (but apparently also stressor, taxon, and
sometimes sex-specific). Clearly the research directions proposed in
this special issue will contribute to a better understanding of these
mechanisms that link environment, lifestyle and telomere dynamics.

At present, telomere research on non-model organisms has been primarily
focused on the endothermic vertebrates - birds and mammals. Nucleated
red blood cells are primarily used in bird studies while white blood
cells are most often in mammals, particularly humans. Thus, tissue
specificity in telomere dynamics associated with these cell types may
itself underlie some of the differences reported. However, the majority
of animals are ectotherms and often differ from many endotherms by
having telomerase production in somatic tissues. Furthermore, many
aspects of ectotherm development and performance are linked to
environmental temperature, and are, therefore, potentially significantly
affected by climate disruption. Friesen et al. (2021) suggest that
developing thermal performance curves for the processes affecting
telomere dynamics could assist in monitoring climate impacts,
highlighting the pressing need for more experimental work in this area
to isolate the causes of environmentally induced changes in telomere
dynamics. Rouan et al. (2021) present such an experimental study on the
coral, \emph{Stylophora pistillata} , in which bleaching, the
devastating loss of symbionts that can results from climate change, was
induced by continuous darkness. This resulted in increased telomere
loss. As well as telling us something about the damaging effects, these
findings could inform methods for monitoring coral reef health. In a
field experiment using young salmon \emph{Salmo salar} , in freshwater
streams, McLennan et al. (2021) found that both a lack of suitable
substrate and living at high density were associated with reduced
telomere length. However, in streams in which nutrient levels were
experimentally restored, these adverse effects on telomere length were
greatly reduced, demonstrating the potential utility of changes in
telomere length in a conservation context. Further, the experiment
presented by Bae et al. (2021) revealed that the effects of temperature
can be influenced by interactions with pollutants. This appears to be
especially prevalent in species with temperature-dependent sex
determination, such as the American alligator\emph{Alligator
mississippiensis} . Here the effect of experimental exposure to an
endocrine disrupting chemical depended on the environmental temperature;
at temperatures promoting female development, the effect on telomere
length was positive, while at the higher, male promoting temperature,
the effect was negative. On the other hand, raising crickets at
different temperatures, which strongly affected their growth, did not
significantly affect their telomere dynamics Boonekamp et al. (2021).
Much may depend on how severely the potential stressor is perceived by
the organism in question.

In a somewhat different context, but still potentially linked to
differences in stress exposure, a non-experimental study by Wood et al.
(2021) used extensive longitudinal assessments of within-individual
rates of change in telomere length to investigate the impacts of
dominance status on telomere dynamics in the cooperative breeder, the
white-browed sparrow-weaver \emph{Plocepasser mahali} . They found that
social dominance and rainfall predicted telomere dynamics. Looking at
mechanistic processes in more detail, Wolf et al. (2021) provided novel
insight into the telomere dynamics of a natural system of tree
swallows\emph{Tachycineta bicolor} , reporting lower expression of the
telomere regulatory gene POT1 in female breeders of higher quality. They
also reported that experimentally induced stress exposure in chicks
induced lower POT1 expression and telomere lengthening.

Collectively, these studies show that variation in stress exposure and
individual resilience can contribute to intra-specific differences in
telomere dynamics. They highlight the need to consider the biology of
the species (including sex differences), the local conditions to which
it has been exposed, what different levels of temperature change mean in
terms of stress exposure for different species and populations, and the
need to examine interacting environmental effects in natural
populations. They also highlight that examining telomere dynamics in
relation to differential expression of relevant genes in relation to
ecological and environmental variables could potentially be of great
interest.

Telomeres and life history trade-offs

Much of the interest in telomeres from ecologists relates to their
potential in mediating life history trade-offs. For example, is
increased telomere damage traded off against potential advantages of
larger size or greater energy expenditure? The outcome of such
trade-offs may be influenced by individual state. Such state-dependent
relationships are difficult to measure but variation in telomere length,
or loss, might provide a relative measure. Carrying elaborate sexual
ornaments is thought to be costly thereby maintaining the honesty of the
signal, but little work has yet been done to test the relative cost of
ornamentation using telomeres. Kauzálová et al. (2022) found that barn
swallows \emph{Hirundo rustica} , with long tail streamers (a sexually
selected ornament (Møller 1988), have shorter telomeres. This suggests a
cost to elaborate ornamentation in this species. Ravindran et al. (2021)
used bivariate analysis to decompose correlations between telomere
length and reproduction into within- and among individual effects. They
conclude that, in wild Soay sheep \emph{Ovis aries} , females had
shorter telomeres in August in years in which they gave birth in spring
compared to years without the gestation effort, indicative of a
trade-off involving reproduction. However, at the same time in years in
which they gave birth, the mother's telomeres were longer when their
lambs survived to August, compared with years when they lost their lambs
earlier, suggesting complex state dependent effects. Sepp et al. (2021)
conducted a cross-fostering experiment in common gulls (\emph{Larus
canus} ), to tease apart pre- and post-natal parental age effects on
offspring telomere length. Neither the age of the natal- nor the foster
parents in this study predicted the length or rate of change of
telomeres in chicks.

The above results are interesting, but also demonstrate that additional
experimental work is needed, particularly in relation to evaluating
parental state-induced telomere dynamics. A good example is provided by
Atema et al. (2021) who manipulated individual state by equipping male
great tits \emph{Parus major} with a `backpack' adding 5\% to their body
mass for a year. Surprisingly telomere dynamics were not affected by
this extra burden, despite the duration of the experiment and large
sample size. However, the absence of an effect was consistent with there
being little evidence of a fitness costs of carrying this extra mass
(Atema et al. 2016), information which is often lacking but critical for
the interpretation of any result. In the dark-eyed junco \emph{Junco
hyemalis} , where experimentally elevated testosterone reduces male
survival (Reed et al. 2006), elevated testosterone was also linked to
accelerated telomere attrition Heidinger et al. (2021). This suggests
that telomere dynamics may be part of the mechanism causing the
testosterone effect on survival in this species, and that variation in
state is an important issue.

Trade-offs involving telomeres may also occur very early in life, for
example, when resources are allocated to growth at the expense of
somatic maintenance, potentially being reflected in early life telomere
dynamics (Monaghan and Ozanne 2018; Vedder et al. 2018). Growth is
difficult to manipulate directly and is often done through dietary
manipulations, which might have confounding systemic effects that can be
difficult to fully take into account. Pepke et al. (2021) examined the
effect of final body size on telomere length within an artificial
selection experiment on body size (tarsus length) in free-living house
sparrows \emph{Passer domesticus} . They studied two island populations,
with selection for large body size on one island, and selection for
small body size on the other. The experiment was successful in creating
a difference in tarsus length between the islands - of almost 10\% in
the final selection year. They found a significant decrease in telomere
length on the island with selection for large body size, but no change
on the island with selection for small body size. The approach of Pepke
et al. (2021) will hopefully be followed by others, potentially using
existing selection experiments on growth and body size. Though to fully
understand the results it may be important to also know more about cell
division rates and growth patterns in the individuals attaining
different body sizes

While the general pattern from human studies is that telomeres shorten
with age, findings in other species, including those in this special
issue mentioned earlier in relation to stress exposure, suggest that
this is not always the case (meta-analysed by Remot et al. 2021 in this
issue). For example, there is evidence of telomere elongation in some
hibernating mammals and snakes (Olsson 2018). This raises questions
about the underlying mechanisms involved in telomere maintenance, with
variation in telomerase activity as a likely candidate. Smith et al.
(2021) review what is known about telomerase activity in ecological
studies and discuss the challenges involved in measuring telomerase
activity. They note that studies have not generally detected the
expected link between telomere maintenance and telomerase activity, for
which there can be different explanations. When telomeres are studied in
blood, it is mainly the telomerase activity in the haemopoietic stem
cells in the bone marrow that will affect the focal telomeres, but
studying this within individuals is very difficult. Noguera et al.
(2020) evaluated the effect of maternal glucocorticoids on telomerase
activity in yellow-legged gulls \emph{Larus michahellis} (e.g.,
corticosterone or cortisol) as their transmission to offspring is a
potential cost associated with adverse or stressful conditions
experienced by mothers. They found that egg corticosterone can stimulate
telomerase activity and promote longer telomeres during embryo
development, suggesting mechanistic links by which mothers may shape
offspring life-history trajectories and phenotypes. In another study,
Sheldon et al. (2021) tested levels of DNA methylation across early life
in wild, nestling zebra finches, discovering that methylation was
negatively correlated with telomere length changes, providing possible
links between epigenetics and telomeres. Altogether, elucidating the
ecology of gene expression and epigenetics in telomere maintenance
across natural populations should therefore be considered an important
task for the future.

Raven et al. (2022) discuss what is known about cancer and telomeres in
the wild, a topic of considerable interest since telomeres have
historically been studied in the context of cancer, with somatic
down-regulation of telomerase postulated as a tumour protection
mechanism in large bodies/long lived species. Telomerase activation has
been identified as critical mutations that are associated with malignant
cells. Raven et al. (2022) emphasize that telomere-cancer dynamics
constitute a complex and a multifaceted process, in part because in
humans both (too) long and (too) short telomeres can be associated with
an increased cancer risk. Whether similar effects can be observed in
natural populations of other species remains to be seen. Telomere length
predicts survival \emph{within} species (Wilbourn et al. 2018), raising
the question as to whether long-lived species have relatively long
telomeres. Among birds, this does not appear to be the case (Tricola et
al. 2018), at least when using the available estimates of maximum
lifespan. In contrast, Gomes et al. (2011) reported an inverse
relationship between telomere length and maximum lifespan in mammals.
Pepke and Eisenberg (2021) revised and extended the data set of Gomes et
al. (2011) and confirmed this inverse relationship. A possible
explanation for this pattern is that short telomeres protect against
cancer, because cells with short telomeres have less scope for
replication before critically short telomeres induce cell replicative
senescence. In line with this explanation, Pepke \& Eisenberg (2021)
show a positive association between telomere length and the development
of neoplasia, abnormal tissue growth that can develop into malignancy.
They further show that domesticated species have substantially longer
telomeres than wild species with similar mass. This may be because of
artificial selection of certain phenotypes, or relaxation of selection
pressures in domestic species; for example domesticated animals will
often be culled before reaching the natural end of their lives,
diminishing selection favouring protection against the development of
cancer.

Heritability and Evolvability

One of the most remarkable aspects of telomere biology is the
considerable range described for the heritability of telomere length
(i.e., the parental genetic contribution additively affecting the
telomere length variance in the offspring, i.e., its
heritability,\emph{h\textsuperscript{2}} = VA/VP). Reviews on telomere
biology report perhaps the widest range in heritability of any
phenotypic trait ranging from near zero to more than one (likely due to
sampling error, since\emph{h\textsuperscript{2}} cannot theoretically
exceed one; Olsson et al. 2018). This makes telomere evolution difficult
to reconcile with evolutionary expectations from existing quantitative
genetics theory, the situation becoming more complex when the aim is to
understand the potential of adaptive telomere evolution and the agents
of selection. An alternative approach to using heritability for this
procedure is to assess `evolvability' as the expected proportional
change under a unit strength of selection, yielding a mean-scaled
additive variance (Houle 1992). These two measures, heritability and
evolvability, have been shown to have near zero correlation, possibly
due to positive correlations between the additive- and other components
of the phenotypic variance (e.g., environmental-, epistatic- and
dominance variance; Hansen 2011). In this special issue, aspects of
quantitative genetics of telomeres and their dynamics are discussed. The
main `other' variance components for understanding telomere
heritability, its limitations and usefulness for evolutionary inference,
are epigenetic inheritance (Bauch et al. 2019), and the environmental
variance (Dugdale and Richardson 2018). A straightforward expectation
from theory is that when environmental variance is eliminated,
heritability will be very high, which is what (Boonekamp et al. 2021;
\emph{h\textsuperscript{2}}\selectlanguage{english}[?] 1) found in their laboratory experiments on
field crickets\emph{Gryllus campestris} . Importantly, heritability
estimates are environment-specific, so to what degree these estimates
predict responses to ongoing telomere selection in the wild remains to
be tested. An attempt to do this in a cross-fostering experiment on
jackdaws \emph{Corvus monedula} , showed that heritability for telomere
length was high (0.74) whereas for telomere shortening rate it was
considerably lower (0.09; Bauch et al. 2021). This agrees with
evolutionary theory in that telomere shortening in this taxon is more
strongly correlated with components of fitness than is telomere
length\emph{per se} (Bauch et al. 2021 and references therein).
Interestingly, Bauch et al.'s evolvability estimate for telomere length
was only 0.48\% and uncorrelated with heritability, in agreement with
Hansen et al.'s evolvability review (2011). In contrast, in a study with
considerably greater sample size and thus power than most QG studies on
telomeres in wild animals Sparks et al. (2021) found low heritability
and evolvability for telomere length in Seychelles warblers, suggesting
differences may exist among species.

Future Directions

The collection of wonderful studies in this special issue demonstrates
the increasing interest in studying telomeres from an evolutionary and
ecological perspective, and their potential value in areas such as
conservation biology. The work reported here highlights several advances
that collectively demonstrate the effect of environment on telomere
dynamics and the corresponding impact on life history trade-offs and
quantitative genetic consequences. In addition, the work also highlights
taxonomic and conceptual areas where additional studies would benefit
the field. For example, recent studies on plants have discovered that
telomerase RNA homologs across the plant kingdom are structurally
similar to ciliates and multicellular eukaryotes, supporting the
hypothesis of a common ancestor for telomerase (Song et al. 2019) . They
also provide growing evidence for the adaptive significance of plant
telomeres for ecologically important traits such as flowering time (Choi
et al. 2021)). However, databases on telomere traits in taxonomically
diverse organisms, with variation in life histories, body sizes, growth
patterns and regenerative capabilities remain limited. More work is
needed on species with complex life cycles, high regenerative capacity
and variable lifespans. Additional studies will hopefully enable testing
of hypotheses of telomere evolutionary history, adaptive life-history
strategies, and chromosomal integrity.

To date, studies of telomere dynamics have benefited from long-term
studies of several animal systems. There is much to be gained from the
within-individual data collected from such studies and variation in
population trajectories. In quantitative genetics (QG), controlling for
individuals having a shared environment between generations (which
inflates the heritability measure) could be achieved by cross-fostering
in many various species and/or and by releasing offspring at random
locations in species without parental care (Olsson et al. 2011), or by
controlling for environmental `type' in longitudinal studies or
experimental plant and animal systems. The large samples necessary for
telomere QG work can be facilitated by choice of appropriate model
systems and by applying emerging techniques in molecular ecology. qPCR
continues to be particularly attractive for high-throughput processing,
especially in species with limited interstitial telomeres (Boonekamp et
al. 2021) (Rovatsos et al. 2015; Matsubara et al. 2015). However, the
potential importance of how interstitial telomere repeats influence the
biology of different taxa has hardly been investigated at all (see
Nussey et al. (Methods in Ecol \& Evolution) for discussion of
methodology). It is important that telomeres measuring methodologies are
as accurate and precise as possible, while allowing for large enough
sample through-put to capture variation. Avoiding problems created by
selective disappearance of phenotypes is also important. Some of these
issues are discussed in this special issue in reviews revealing major
methodological effects on estimates of individual repeatability
(Karkkainen et al. 202xb) and heritability (Bauch et al. 2021).

A recently developed method, the single telomere absolute-length rapid
(STAR) assay offers a high-throughput, digital real-time PCR approach
for rapidly measuring the absolute lengths and quantities of individual
telomere molecules (Luo et al. 2020) (Dwech-Maitre et al 021), although
its precision remains to be evaluated. In the future the use of digital
qPCR may yield higher throughput than traditional Telomere Restriction
Fragment analysis (TRF) (Nussey et al 2014) and more precision than
current qPCR methods. Pepke et al. (2021) examined heritability and
genetic architecture using a combination of qPCR and next generation
sequencing, supporting that new bioinformatic approaches using
computerized telomere estimation may facilitate higher throughput and
examination of non-terminal telomeres and their position effects on
fitness (Nersisyan and Arakelyan 2015; Edwards 2021).

Finally, many exciting questions pertaining to telomere biology in
relation to ecology evolution and conservation remain to be answered.
For evolutionary biologists and ecologists, variation is the `stuff of
life' and understanding the causes and consequences of such variation,
and the role of telomeres within that is an important and exciting
challenge! We still know relatively little about how flexible telomere
biology is under different selection pressures and to what extent it
constrains the suite of potential life histories, for example in
relation to growth, body size, reproduction and lifespan. In terms of
fitness, we may ask what matters most, telomere loss or telomere length?
Both length and loss rate have been found to be predictive of longevity
within species and much may depend on the life stage at which each is
measured; it seems unlikely that limited telomere length would curtail
lifespan until relatively old age, when stem cell pools are depleted and
stem cells themselves show age-related deterioration. That said,
telomere loss might give us a better handle on understanding stress
exposure and stress resilience. In humans and birds, there is evidence
that telomere length variation stabilises at the end of growth and that
telomere length at this time period is the best predictor of subsequent
lifespan (Benetos et al. 2013, Daniali et al. 2013, Heidinger et al
2012). Will similar patterns be revealed in species with indeterminate
growth? Currently, we simply do not have the data to answer this
question so much more work is needed in this area. In a conservation
context, can telomere biology help us identify populations at risk from
rapid environmental disruption due to anthropogenic effects, and
identify species that are likely to be resilient to climate change and
stress exposure? Given that the genetic basis of adaptive traits are now
used to project the distribution of species in response to climate
change (Wuitchik et al. 2022), it is possible that the inclusion of
telomere biology may further inform and refine such projections in
species distribution models.

Altogether, this comprehensive collection of studies demonstrates the
enormous potential for the integration of ecological and genomic
approaches to continue to transform our understanding of the
consequences of intrinsic and extrinsic environmental stressors and
change on the ecology and evolution of natural populations. This special
issue highlights how a deeper appreciation of the role of telomeres and
associated properties of the genome will continue to benefit the field
of Molecular Ecology.

Literature Cited

A.P, Moller. 1988. ``Female Choice Selects for Male Sexual Tail
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