Software by Kevin Arbuckle
Papers by Kevin Arbuckle
Reproduction is an energetically costly activity and so is often timed to occur when conditions a... more Reproduction is an energetically costly activity and so is often timed to occur when conditions are most favorable. However, human-induced changes in long-term, seasonal, and short-term climatic conditions have imposed negative consequences for reproduction across a range of mammals. Whilst the effect of climate change on reproduction in temperate species is well known, its effect on equatorial species is comparatively understudied. We used long-term ecological data (~20 yr) to investigate the impact of changes in rainfall and temperature on reproduction in an equatorial mammal, the banded mongoose (Mungos mungo). After controlling for the effects of group-size, we found that more females were pregnant and gave birth following periods of high seasonal rainfall, pregnancies increased at higher seasonal temperatures, and births increased with long-term rainfall. This is likely beneficial as high rainfall is positively associated with pup growth and survival. Females cannot, however, carry and raise pups over the course of a single wet season, so females face a trade-off in reproductive timing between maximizing resource availability during gestation or the early life of pups, but not both. Since the duration of the wet seasons is predicted to increase with climate change, the optimum conditions for banded mongoose reproduction may be extended. However, the potential benefits of extended wet seasons may be counteracted by the negative impacts of high temperatures on pup growth and survival. Our results highlight the importance of seasonality in reproduction of tropical mammals and the complex impacts of anthropogenic climate change on recruitment in equatorial species.
Public donations are an important form of fundraising for zoos and are used to support conservati... more Public donations are an important form of fundraising for zoos and are used to support conservation activities. Understanding what influences zoo animal sponsorship by the public is crucial if zoos are to optimize strategies for increasing income from sponsors. Using sponsorship data obtained from seven
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
CROTAPHOPELTIS HOTAMBOEIA (White-lipped Herald Snake). COLOR CHANGE. Crotaphopeltis hotamboeia is... more CROTAPHOPELTIS HOTAMBOEIA (White-lipped Herald Snake). COLOR CHANGE. Crotaphopeltis hotamboeia is a common nocturnal colubrine that is widespread in Sub-Saharan Africa and found throughout East Africa, with the exception of arid areas (Pitman 1974. A Guide to the Snakes of Uganda, revised ed. Wheldon & Wesley, Ltd. Codicote, UK. 290 pp.; Spawls et al. 2018. Field Guide to East African Reptiles. 2 nd ed. Bloomsbury Publishing. London, UK. 624 pp.). The color pattern of this species is variable, with background color ranging from black through grey to various shades of brown or yellow, typically with white speckling or broken crossbars and paler supralabial scales (Pitman 1974, op. cit.; Spawls et al. 2018, op. cit.). Lighter colored snakes often have a dark grey to black temporal patch on their heads. Ugandan specimens are reported as being predominantly greenish-brown through black, with speckling sometimes indistinct and only rarely with white supralabials, which are more usually dusky brown (Pitman 1974, op. cit.). Color change in snakes is best known in the form of slow seasonal or ontogenetic change over the lifespan of a snake, such as the dramatic color change of green tree pythons (Morelia viridis) from juvenile to adults (Wilson et al. 2007. Biol. Lett. 3:40-43). Nevertheless, a few examples of reversible physiological color change have been reported in snakes including various
Spider webs, and in particular orb webs, are among the most iconic characteristics of spider biol... more Spider webs, and in particular orb webs, are among the most iconic characteristics of spider biology. The evolution of, and developmental changes in, orb webs have been well studied, but we still have a limited understanding of allometric relations between the size of orb webs and spider body size. In this study, we investigate this relationship using measurements from 55 individuals of two common orb-weaving spider (Araneidae) species in South Wales, UK. We recorded body size using two methods: direct measurements with calipers, and estimations from photographs using ImageJ software. We found that these two methods give almost identical measurements, supporting the use of image-based size measurement in many situations where this is advantageous. We also found evidence for negative allometry of orb web size (relative to spider body length), such that larger spiders build proportionately smaller webs. This implies that the 'giant webs' in some orb-weaver species must be the result of a fundamental shift in the constraints or advantages which result in the allometric relationships described here.
Life-history theory suggests that individuals should reproduce until death, yet females of a smal... more Life-history theory suggests that individuals should reproduce until death, yet females of a small number of mammals live for a significant period after ceasing reproduction, a phenomenon known as post-reproductive lifespan. It is thought that the evolution of this trait is facilitated by increasing local relatedness throughout a female's lifetime. This allows older females to gain inclusive fitness through helping their offspring (known as a mother effect) and/or grandoffspring (known as a grandmother effect), rather than gaining direct fitness through reproducing. However, older females may only benefit from stopping reproducing when their direct offspring compete with those of their daughters. Here, we investigate whether a lack of post-reproductive lifespan in long-finned pilot whales (Globicephala melas) results from minimal benefits incurred from the presence of older females, or from a lack of costs resulting from mother-daughter co-reproduction. Using microsatellite data, we conducted parentage analysis on individuals from 25 pods and find that younger females were more likely to have offspring if their mother was present in their pod, indicating that mothers may assist inexperienced daughters to reproduce. However, we found no evidence of reproductive conflict between co-reproducing mothers and daughters, indicating that females may be able to reproduce into old age while simultaneously aiding their daughters in reproduction. This highlights the importance of reproductive conflict in the evolution of a post-reproductive lifespan and demonstrates that mother and grandmother effects alone do not result in the evolution of a postreproductive lifespan.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-... more This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Figure 1. Illustration of high density of Teira dugesii on a representative wall with holes for s... more Figure 1. Illustration of high density of Teira dugesii on a representative wall with holes for shelter. This style of wall is common throughout the island and is a frequent lizard habitat.
Chameleons are charismatic and common lizards across Madagascar, Africa, and some surrounding reg... more Chameleons are charismatic and common lizards across Madagascar, Africa, and some surrounding regions. Little is known about their diversification dynamics and how this relates to their ecology, so we estimated diversification rate variation and consider this in the context of three hypotheses previously proposed in the literature. First, that the transoceanic dispersal from Africa to Madagascar on two separate occasions has resulted in fast radiation of Malagasy chameleons. Second, that the substantial floral turnover in their distributions within South Africa has resulted in rapid radiations of the endemic dwarf chameleons (Bradypodion). Finally, that the evolution of distinct ecomorphs of chameleon has fuelled fast diversification via adaptive radiations. We use the most recent and complete phylogeny of chameleons to estimate the diversification dynamics of the group using three methods: BAMM (which estimates constant or gradually changing diversification regimes and tests for shifts in these), MEDUSA (which tests for rate shifts in particular clades), and ClaDS (which estimates branch-specific diversification rates). Our results from all analyses estimate a diversification rate increase in a clade containing most of the genus Bradypodion, a group containing the South African dwarf chameleons which occur in recognized biodiversity hotspots in diverse habitats. We find no evidence for shifts resulting from dispersal events to Madagascar or related to the strong ecomorphological divergence of short-tailed chameleon lineages (Brookesia, Palleon, Rhampholeon, and Rieppeleon). The single burst of diversification within chameleons was in a clade which was associated with geographic areas which have experienced rapid habitat turnover and vicariance over the last 10 million years. This suggests that 'habitat vicariance' resulting from ecological changes in vegetation has contributed to the diversity of species in this area by increasing diversification rates.
Cooperative breeding, in which individuals other than the parents assist in the production of you... more Cooperative breeding, in which individuals other than the parents assist in the production of young, occurs in around 9% of birds (Cockburn, 2006). It often arises when offspring remain on their parents' territory after gaining nutritional independence and become "helpers at the nest," assisting in rearing subsequent broods (Ligon & Burt, 2004). This helping behavior presents several potential costs, for instance, helpers sometimes forgo their own reproduction in order to help-usually gaining indirect fitness (if helping kin) but at a cost to direct fitness (Dickinson & Hatchwell, 2004). Importantly, even if no immediate opportunities
attempted to swallow the prey for several minutes, but eventually gave up and moved away. Parus m... more attempted to swallow the prey for several minutes, but eventually gave up and moved away. Parus major appears to be a previously unreported prey for N. helvetica, while for E. rubecula, there was an old record based on stomach content (Rogers 1901, op. cit.); a brief review of bird consumption records by "grass snakes" is shown in Table 1. Since there are now three documented instances of active predation by N. helvetica on living fledglings of resident birds, this behavior, although uncommon, is clearly not abnormal. New direct observations of such events are needed to examine in greater detail this kind of feeding behavior, including the circumstances (all three observations took place in the afternoon during May and June) and the involved species (all bird species in Table 1 are yearround residents of the regions where the observations took place). We are grateful to Franco Ierardi and Alexandre Roux for the observation data and for allowing us to use photos and videos, to Gaia Bazzi, Mirko Galuppi and Andrea Ambrogio for their advice, and to John D. Willson and Andrew Durso for their review which improved the work.
In species that live in family groups, such as cooperative breeders, inbreeding is usually avoide... more In species that live in family groups, such as cooperative breeders, inbreeding is usually avoided through the recognition of familiar kin. For example, individuals may avoid mating with conspecifics encountered regularly in infancy, as these likely include parents, siblings, and closely related alloparents. Other mechanisms have also been reported, albeit rarely; for example, individuals may compare their own phenotype to that of others, with close matches representing likely relatives ("phenotype matching"). However, determinants of the primary inbreeding avoidance mechanisms used by a given species remain poorly understood. We use 24 years of life history and genetic data to investigate inbreeding avoidance in wild cooperatively breeding banded mongooses (Mungos mungo). We find that inbreeding avoidance occurs within social groups but is far from maximised (mean pedigree relatedness between 351 breeding pairs = 0.144). Unusually for a group-living vertebrate, we find no evidence that females avoid breeding with males with which they are familiar in early life. This is probably explained by communal breeding; females give birth in tight synchrony and pups are cared for communally, thus reducing the reliability of familiarity-based proxies of relatedness. We also found little evidence that inbreeding is avoided by preferentially breeding with males of specific age classes. Instead, females may exploit as-yet unknown proxies of relatedness, for example, through phenotype matching, or may employ postcopulatory inbreeding avoidance mechanisms. Investigation of species with unusual breeding systems helps to identify constraints against inbreeding avoidance and contributes to our understanding of the distribution of inbreeding across species. Significance statement Choosing the right mate is never easy, but it may be particularly difficult for banded mongooses. In most social animals, individuals avoid mating with those that were familiar to them as infants, as these are likely to be relatives. However, we show that this rule does not work in banded mongooses. Here, the offspring of several mothers are raised in large communal litters by their social group, and parents seem unable to identify or direct care towards their own pups. This may make it difficult to recognise relatives based on their level of familiarity and is likely to explain why banded mongooses frequently inbreed. Nevertheless, inbreeding is lower than expected if mates are chosen at random, suggesting that alternative pre-or post-copulatory inbreeding avoidance mechanisms are used.
Background: Understanding drivers of animal biodiversity has been a longstanding aim in evolution... more Background: Understanding drivers of animal biodiversity has been a longstanding aim in evolutionary biology. Insects and fishes represent the largest lineages of invertebrates and vertebrates respectively, and consequently many ideas have been proposed to explain this diversity. Natural enemy interactions are often important in diversification dynamics, and key traits that mediate such interactions may therefore have an important role in explaining organismal diversity. Venom is one such trait which is intricately bound in antagonistic coevolution and has recently been shown to be associated with increased diversification rates in tetrapods. Despite ~ 10% of fish families and ~ 16% of insect families containing venomous species, the role that venom may play in these two superradiations remains unknown. Results: In this paper we take a broad family-level phylogenetic perspective and show that variation in diversification rates are the main cause of variations in species richness in both insects and fishes, and that venomous families have diversification rates twice as high as non-venomous families. Furthermore, we estimate that venom was present in ~ 10% and ~ 14% of the evolutionary history of fishes and insects respectively. Conclusions: Consequently, we provide evidence that venom has played a role in generating the remarkable diversity in the largest vertebrate and invertebrate radiations.
This is an open access article under the terms of the Creat ive Commo ns Attri bution License, wh... more This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Software by Kevin Arbuckle
Papers by Kevin Arbuckle