Mainland size variation informs predictive models of exceptional insular body size change in rodents

Durst, Paul A. P.; Roth, V. Louise

doi:10.1098/rspb.2015.0239

Cited by 21 publications

(26 citation statements)

References 27 publications

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“…The island rule, like Bergmann's rule, may prove to be taxon‐specific in mammals (Meiri et al., ), with species within a given order typically following a common pattern. For example, rodent species, with some exceptions, typically evolve larger body size on islands (Durst & Roth, ), and patterns found among primates support the island rule as well (Bromham & Cardillo, ; Welch, ). In contrast, the apparent lack of support for the island rule in the common treeshrew may prove to be the common pattern throughout Scandentia.…”

Section: Discussionmentioning

confidence: 98%

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Sargis

Millien

Woodman

et al. 2018

Ecology and Evolution

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There are a number of ecogeographical “rules” that describe patterns of geographical variation among organisms. The island rule predicts that populations of larger mammals on islands evolve smaller mean body size than their mainland counterparts, whereas smaller‐bodied mammals evolve larger size. Bergmann's rule predicts that populations of a species in colder climates (generally at higher latitudes) have larger mean body sizes than conspecifics in warmer climates (at lower latitudes). These two rules are rarely tested together and neither has been rigorously tested in treeshrews, a clade of small‐bodied mammals in their own order (Scandentia) broadly distributed in mainland Southeast Asia and on islands throughout much of the Sunda Shelf. The common treeshrew, Tupaia glis, is an excellent candidate for study and was used to test these two rules simultaneously for the first time in treeshrews. This species is distributed on the Malay Peninsula and several offshore islands east, west, and south of the mainland. Using craniodental dimensions as a proxy for body size, we investigated how island size, distance from the mainland, and maximum sea depth between the mainland and the islands relate to body size of 13 insular T. glis populations while also controlling for latitude and correlation among variables. We found a strong negative effect of latitude on body size in the common treeshrew, indicating the inverse of Bergmann's rule. We did not detect any overall difference in body size between the island and mainland populations. However, there was an effect of island area and maximum sea depth on body size among island populations. Although there is a strong latitudinal effect on body size, neither Bergmann's rule nor the island rule applies to the common treeshrew. The results of our analyses demonstrate the necessity of assessing multiple variables simultaneously in studies of ecogeographical rules.

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Section: Discussionmentioning

confidence: 98%

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Sargis

Millien

Woodman

et al. 2018

Ecology and Evolution

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“…The principal product of RTA is a recursively branching tree that describes the direct, interactive and contextual relationships between the response variable (here Si) and a subset of the predictor variables (geographic and ecological variables) (see e.g. Durst & Roth, , ; Lomolino et al., , ; Lyons et al., ; Van der Geer et al., for descriptions and application of classification and regression tree analyses to body size patterns). For each RTA, I obtained an optimal tree, selected based on K‐fold cross‐validation, and a maximal tree, produced by growing interactively the respective optimal tree as large as possible (SAS Institute, ).…”

Section: Methodsmentioning

confidence: 99%

“…In particular, although the majority of island bovids, as large mammals, do follow the main prediction of the island rule, showing a body size reduction (Figure 1), the island rule pattern is not clearly exhibited across all species/subspecies of insular bovids combined (Figure 1). Much variation about the analysed island rule trends (r 2 values ranging from about .03 to .60; see Table 2) is, however, to be expected given the variation among islands in terms of characteristics proposed to influence evolution of body size of insular mammals (in particular, predatory and competitive release; Durst & Roth, 2015;Lomolino et al, 2012). Furthermore, it is worth noting the presence on different islands (e.g.…”

Section: Generality Of the Island Rule In Bovidsmentioning

confidence: 99%

“…Faurby & Svenning, ; Lomolino, , ; Lomolino et al., , ; McClain et al., ; Meiri et al., ; Van der Geer et al., ), investigations of the island rule pattern in insular mammals have mainly focused on proboscideans and rodents, which include the most spectacular cases of dwarfism and gigantism, respectively (see e.g. Durst & Roth, , ; Palombo, ; Van den Hoek Ostende, Van der Geer, & Wijngaarden, ; Van der Geer, Van den Bergh, et al., ). Bovidae is a highly diverse clade of large mammals (Bibi, ; Bibi et al., ; Hernández Fernández & Vrba, ) and encompasses several insular species that inhabited or are still living on islands located in different regions and characterized by different environmental features and palaeogeographic histories.…”

Section: Introductionmentioning

confidence: 99%

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Space–time patterns of body size variation in island bovids: The key role of predatory release

Rozzi

2018

Journal of Biogeography

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Aim I provide the first comprehensive study on body size evolution of extinct and living insular bovids, exploring the causal biotic and abiotic selective factors for observed patterns. Location Islands worldwide. Methods I assembled data on the geographic characteristics of 13 focal islands (area, isolation, latitude, net primary productivity) and on the ecological and morphological characteristics of 32 insular bovid taxa (number of predators and competitors, richness of large mammals, body mass of mainland relatives). I used linear regressions and machine learning methods (regression trees and random forest analyses) to examine the hypothesized contextual importance of these factors in explaining variation in the body size of island bovids. I also calculated evolutionary rates of body size divergence of focal taxa in order to assess whether this phenomenon is influenced by time in isolation. Results The results of regression, regression tree and random forest analyses were in agreement with predictions based on a hypothesis of ecological release (more pronounced body size divergence on islands with the fewest competitors and predators). Only limited support for a resource limitation hypothesis (more pronounced body size divergence for the larger taxa on smaller islands) was found. Main conclusions The majority of insular bovids, as large mammals, do follow the main prediction of the island rule, exhibiting body size reduction, and predator diversity is the main factor influencing body size evolution of these taxa. Results obtained highlighted the crucial role of time in isolation, with body size reduction becoming more pronounced for bovids with longer residence times on the islands.

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“…In many rodent species, island populations differ significantly in size from mainland relatives and populations without predators (Goldwater et al 2012;Durst & Roth 2015) and this trend has been documented in New Zealand mice (Russell 2012). Each mouse in our sample was weighed (balance accurate to 0.01 g), and, because each population sample contained mice of different ages, we analysed morphological variation using an ANOVA-like Generalized Linear Model (GLM) fitted using the linear model (lm) function in the R statistical program, version 3.0.1.…”

Section: Morphological Analysismentioning

confidence: 99%

Genetic distinctiveness of the Waikawa Island mouse population indicates low rate of dispersal from mainland New Zealand

Bradley¹,

Trewick²,

Morgan‐Richards³

2017

NZ J Ecol

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Abstract:In New Zealand, mice in reserves can complicate the control of mammalian predator invasion by masking scent and eating baits. Eradicating mice allows predator invasions to be more readily detected and managed, but removal of mice is only feasible if recolonisation is rare. We used genetics and morphology to assess whether the mouse population on Waikawa Island was isolated from the mainland population. A sample of mitochondrial DNA sequences revealed that at least four female mice must have founded the Waikawa population, but that gene flow between island and mainland mice is limited. Although no variation in DNA sequences of exon 1 of the nuclear gene vitamin K 2,3-epoxide reductase subcomponent 1 was detected, the common allele is not associated with resistance to anticoagulant rodenticides such as warfarin. Body size comparisons revealed the island population as distinct, possibly due to age structure differences. We infer low levels of successful dispersal between the mainland and Waikawa Island mouse populations and suggest eradication might be sustainable in the long-term if protection against rodent invasion is maintained.

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Mainland size variation informs predictive models of exceptional insular body size change in rodents

Cited by 21 publications

References 27 publications

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Space–time patterns of body size variation in island bovids: The key role of predatory release

Genetic distinctiveness of the Waikawa Island mouse population indicates low rate of dispersal from mainland New Zealand

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