Ecomorphological and phylogenetic controls on sympatry across extant bats

AimMacroecological patterns of sympatry can inform our understanding of how ecological and evolutionary processes govern species distributions. Following speciation, both intrinsic and extrinsic factors may determine how readily sympatry occurs. One possibility is that sympatry most readily occurs with ecological divergence, especially if broad‐scale co‐occurrence is mediated by niche differentiation. Time since divergence may also predict sympatry if hybridization and gene flow lead to the collapse of species boundaries between closely related taxa. Here, we test for ecological and phylogenetic predictors of sympatry across the global radiation of extant bats.LocationGlobal.TaxonBats (Order Chiroptera).MethodsWe used a combination of linear mixed‐modelling, simulations and maximum‐likelihood modelling to test whether phylogenetic and ecomorphological divergence between species predict sympatry. We further assess how these relationships vary based on biogeographic realm.ResultsWe find that time since divergence does not predict sympatry in any biogeographic realm. Morphological divergence is negatively related to sympatry in the Neotropics, but shows no relationship with sympatry elsewhere.Main conclusionsWe find that bats in most biogeographic realms co‐occur at broad spatial scales regardless of phylogenetic similarity. Neotropical bats, however, appear to co‐occur most readily when morphologically similar. To the extent that pairwise phylogenetic and morphological divergence reflect ecological differentiation, our results suggest that abiotic and environmental factors may be more important than species interactions in determining patterns of sympatry across bats.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/1/jbi13353-sup-0005-FigureS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/2/jbi13353.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/3/jbi13353-sup-0006-FigureS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/4/jbi13353-sup-0003-FigureS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/5/jbi13353-sup-0004-FigureS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/6/jbi13353_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/7/jbi13353-sup-0002-FigureS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/8/jbi13353-sup-0001-FigureS1.pd

Reproduction triggers adaptive increases in body size in female mole-rats

In social mole-rats, breeding females are larger and more elongated than non-breeding female helpers. This status-related morphological divergence is thought to arise from modifications of skeletal growth following the death or removal of the previous breeder and the transition of their successors from a non-breeding to a breeding role. However, it is not clear what changes in growth are involved, whether they are stimulated by the relaxation of reproductive suppression or by changes in breeding status, or whether they are associated with fecundity increases. Here, we show that, in captive Damaraland mole-rats (Fukomys damarensis), where breeding was experimentally controlled in age-matched siblings, individuals changed in size and shape through a lengthening of the lumbar vertebrae when they began breeding. This skeletal remodelling results from changes in breeding status because (i) females removed from a group setting and placed solitarily showed no increases in growth and (ii) females dispersing from natural groups that have not yet bred do not differ in size and shape from helpers in established groups. Growth patterns consequently resemble other social vertebrates where contrasts in size and shape follow the acquisition of the breeding role. Our results also suggest that the increases in female body size provide fecundity benefits. Similar forms of socially responsive growth might be more prevalent in vertebrates than is currently recognized, but the extent to which this is the case, and the implications for the structuring of mammalian dominance hierarchies, are as yet poorly understood.The Kalahari Mole-rat Project is supported by a European Research Council Grant awarded to T.C.-B. (no. 294494); J.T. was funded by a Natural Environment Research Council Doctoral Training Program; parts of the fieldwork were funded by a British Ecological Society Grant awarded to Markus Zöttl (no. 5301/6343).http://rspb.royalsocietypublishing.org2019-06-13hj2018Mammal Research InstituteZoology and Entomolog

Oxidative costs of cooperation in cooperatively breeding Damaraland mole-rats

Within cooperatively breeding societies, individuals adjust cooperative contributions to maximize indirect fitness and minimize direct fitness costs. Yet, little is known about the physiological costs of cooperation, which may be detrimental to direct fitness. Oxidative stress, the imbalance between reactive oxygen species (by-products of energy production) and antioxidant protection, may represent such a cost when cooperative behaviours are energetically demanding. Oxidative stress can lead to the accumulation of cellular damage, compromising survival and reproduction, thus mediating the trade-off between these competing life-history traits. Here, we experimentally increased energetically demanding cooperative contributions in captive Damaraland mole-rats (Fukomys damarensis). We quantified oxidative stress-related effects of increased cooperation on somatic and germline tissues, and the trade-off between them. Increased cooperative contributions induced oxidative stress in females and males, without increasing somatic damage. Males accumulated oxidative damage in their germline despite an increase in antioxidant defences. Finally, oxidative damage accumulation became biased towards the germline, while antioxidant protection remained biased towards the soma, suggesting that males favour the maintenance of somatic tissues (i.e. survival over reproduction). Our results show that heightened cooperative contributions can ultimately affect direct fitness through oxidative stress costs, which may represent a key selective pressure for the evolution of cooperation.A Postgraduate Research Support bursary awarded by the University of Pretoria; Department of Science and Technology/ National Research Foundation SARChI chair in Behavioural Ecology and Physiology; the Swiss National Science Foundation and animal husbandry and facilities at the Kalahari Research Centre were funded by European Research Council Advanced Grants.http://royalsocietypublishing.org/journal/rspbhj2021Mammal Research InstituteZoology and Entomolog

Reproduction triggers adaptive increases in body size in female mole-rats

In social mole-rats, breeding females are larger and more elongated than nonbreeding female helpers. The status-related morphological divergence is thought to arise from modifications of skeletal growth following the death or removal of the previous breeder and the transition of their successors from a nonbreeding to a breeding role. However, it is not clear what changes in growth are involved, whether they are stimulated by the relaxation of reproductive suppression or by changes in breeding status, or whether they are associated with fecundity increases. Here, we show that, in captive Damaraland mole-rats (Fukomys damarensis) where breeding was experimentally controlled in age-matched siblings, individuals changed in size and shape through a lengthening of the lumbar vertebrae when they began breeding. This skeletal remodelling results from changes in breeding status since i) females removed from a group setting and placed solitarily showed no increases in growth, and ii) females dispersing from natural groups that have not yet bred do not differ in size and shape from helpers in established groups. Growth patterns consequently resemble other social vertebrates where contrasts in size and shape follow acquisition of the breeding role. Our results also suggest that the increases in female body size provide fecundity benefits. Similar forms of socially responsive growth might be more prevalent in vertebrates than is currently recognised, but the extent to which this is the case, and the implications for the structuring of mammalian dominance hierarchies, is as yet poorly understood.The Kalahari Mole-rat Project is supported by a European Research Council Grant awarded to TCB (#294494); JT was funded by a Natural Environment Research Council Doctoral Training Program; Parts of the fieldwork were funded by a British Ecological Society Grant awarded to Markus Zöttl (#5301/6343)

Data from: Reproduction triggers adaptive increases in body size in female mole-rats

In social mole-rats, breeding females are larger and more elongated than nonbreeding female helpers. The status-related morphological divergence is thought to arise from modifications of skeletal growth following the death or removal of the previous breeder and the transition of their successors from a nonbreeding to a breeding role. However, it is not clear what changes in growth are involved, whether they are stimulated by the relaxation of reproductive suppression or by changes in breeding status, or whether they are associated with fecundity increases. Here, we show that, in captive Damaraland mole-rats (Fukomys damarensis) where breeding was experimentally controlled in age-matched siblings, individuals changed in size and shape through a lengthening of the lumbar vertebrae when they began breeding. This skeletal remodelling results from changes in breeding status since i) females removed from a group setting and placed solitarily showed no increases in growth, and ii) females dispersing from natural groups that have not yet bred do not differ in size and shape from helpers in established groups. Growth patterns consequently resemble other social vertebrates where contrasts in size and shape follow acquisition of the breeding role. Our results also suggest that the increases in female body size provide fecundity benefits. Similar forms of socially responsive growth might be more prevalent in vertebrates than is currently recognised, but the extent to which this is the case, and the implications for the structuring of mammalian dominance hierarchies, is as yet poorly understood

Data from: Ecomorphological and phylogenetic controls on sympatry across extant bats

Aim: Macroecological patterns of sympatry can inform our understanding of how ecological and evolutionary processes govern species distributions. Following speciation, both intrinsic and extrinsic factors may determine how readily sympatry occurs. One possibility is that sympatry most readily occurs with ecological divergence, especially if broad-scale co-occurrence is mediated by niche differentiation. Time since divergence may also predict sympatry if hybridization and gene flow lead to the collapse of species boundaries between closely-related taxa. Here, we test for ecological and phylogenetic predictors of sympatry across the global radiation of extant bats. Location: Global Taxon: Bats (Order Chiroptera) Methods: We used a combination of linear mixed modeling, simulations, and maximum-likelihood modeling to test whether phylogenetic and ecomorphological divergence between species predict sympatry. We further assess how these relationships vary based on biogeographic realm. Results: We find that time since divergence does not predict sympatry in any biogeographic realm. Morphological divergence is negatively related to sympatry in the Neotropics, but shows no relationship with sympatry elsewhere. Main conclusions: We find that bats in most biogeographic realms co-occur at broad spatial scales regardless of phylogenetic similarity. Neotropical bats, however, appear to co-occur most readily when morphologically similar. To the extent that pairwise phylogenetic and morphological divergence reflect ecological differentiation, our results suggest that abiotic and environmental factors may be more important than species interactions in determining patterns of sympatry across bats

Details of study system, supplementary tables and figures. from Reproduction triggers adaptive increases in body size in female mole-rats

In social mole-rats, breeding females are larger and more elongated than non-breeding female helpers. The status-related morphological divergence is thought to arise from modifications of skeletal growth following the death or removal of the previous breeder and the transition of their successors from a non-breeding to a breeding role. However, it is not clear what changes in growth are involved, whether they are stimulated by the relaxation of reproductive suppression or by changes in breeding status, or whether they are associated with fecundity increases. Here, we show that, in captive Damaraland mole-rats (<i>Fukomys damarensis</i>) where breeding was experimentally controlled in age-matched siblings, individuals changed in size and shape through a lengthening of the lumbar vertebrae when they began breeding. This skeletal remodelling results from changes in breeding status because (i) females removed from a group setting and placed solitarily showed no increases in growth and (ii) females dispersing from natural groups that have not yet bred do not differ in size and shape from helpers in established groups. Growth patterns consequently resemble other social vertebrates where contrasts in size and shape follow the acquisition of the breeding role. Our results also suggest that the increases in female body size provide fecundity benefits. Similar forms of socially responsive growth might be more prevalent in vertebrates than is currently recognized, but the extent to which this is the case, and the implications for the structuring of mammalian dominance hierarchies, is as yet poorly understood

Details of study system, supplementary tables and figures. from Reproduction triggers adaptive increases in body size in female mole-rats

In social mole-rats, breeding females are larger and more elongated than non-breeding female helpers. This status-related morphological divergence is thought to arise from modifications of skeletal growth following the death or removal of the previous breeder and the transition of their successors from a non-breeding to a breeding role. However, it is not clear what changes in growth are involved, whether they are stimulated by the relaxation of reproductive suppression or by changes in breeding status, or whether they are associated with fecundity increases. Here, we show that, in captive Damaraland mole-rats (<i>Fukomys damarensis</i>), where breeding was experimentally controlled in age-matched siblings, individuals changed in size and shape through a lengthening of the lumbar vertebrae when they began breeding. This skeletal remodelling results from changes in breeding status because (i) females removed from a group setting and placed solitarily showed no increases in growth and (ii) females dispersing from natural groups that have not yet bred do not differ in size and shape from helpers in established groups. Growth patterns consequently resemble other social vertebrates where contrasts in size and shape follow the acquisition of the breeding role. Our results also suggest that the increases in female body size provide fecundity benefits. Similar forms of socially responsive growth might be more prevalent in vertebrates than is currently recognized, but the extent to which this is the case, and the implications for the structuring of mammalian dominance hierarchies, are as yet poorly understood

Increases in glucocorticoids are sufficient but not necessary to increase cooperative burrowing in Damaraland mole-rats.

Despite widespread interest in the evolution of cooperative behaviour, the physiological mechanisms shaping their expression remain elusive. We tested the hypothesis that glucocorticoid (GC) hormones affect cooperative behaviour using captive Damaraland mole-rats (Fukomys damarensis), a cooperatively breeding mammal. Within groups, individuals routinely contribute to public goods that include foraging tunnels, which provide all group members access to the tubers of desert plants they feed on, communal food stores and nests. We found that experimental increases in glucocorticoid concentration (GCc) in non-breeding female helpers led them to be active for longer and to burrow more while active, raising their daily contributions to burrowing, but not food carrying or nest building. However, experimentally induced increases in burrowing did not lead to elevated GCc in helpers of both sexes. These results suggest that heightened GCc may stimulate some cooperative behaviours that are energetically demanding (a characteristic shared by many types of cooperative activities across species) but that the cooperative behaviours affected by GCc can also be regulated by other mechanisms.European Research Counci

DataforThorley_DMRMorphology

Morphology data for female Damaraland mole-rats derived from X-rays taken in captive and wild mole-rats. Data contains a cross-sectional dataset in captivity, a cross-sectional dataset in the wild, and a longitudinal dataset in captivity (collected as part of an experiment)