Mating system and brain size in bats

Pitnick, Scott; Jones, Kate E.; Wilkinson, Gerald S.

doi:10.1098/rspb.2005.3367

Cited by 162 publications

(228 citation statements)

References 60 publications

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“…However, Garamszegi et al (2005b) used residuals to control for allometry, which could lead to biased parameter estimates (Freckleton 2002). Conversely, in bats, intense sexual selection was associated with a decrease in brain size, possibly due to a trade-off between brain and testis size (Pitnick et al 2006); however, the lack of data on sexed individuals precluded the analysis of sex-specific effects. A previous study with Tanganyikan cichlids suggested that monogamous species had a larger telencephalon and a smaller hypothalamus (Pollen et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Social fishes and single mothers: brain evolution in African cichlids

2008

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As with any organ, differences in brain size-after adequate control of allometry-are assumed to be a response to selection. With over 200 species and an astonishing diversity in niche preferences and social organization, Tanganyikan cichlids present an excellent opportunity to study brain evolution. We used phylogenetic comparative analyses of sexed adults from 39 Tanganyikan cichlid species in a multiple regression framework to investigate the influence of ecology, sexual selection and parental care patterns on whole brain size, as well as to analyse sex-specific effects. First, using species-specific measures, we analysed the influence of diet, habitat, form of care (mouthbrooding or substrate guarding), care type (biparental or female only) and intensity of sexual selection on brain size, while controlling for body size. Then, we repeated the analyses for male and female brain size separately. Type of diet and care type were significantly correlated with whole brain size. Sex-specific analyses showed that female brain size correlated significantly with care type while male brain size was uncorrelated with care type. Our results suggest that more complex social interactions associated with diet select for larger brains and further that the burden of uniparental care exerts high cognitive demands on females.

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Section: Discussionmentioning

confidence: 99%

Social fishes and single mothers: brain evolution in African cichlids

2008

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“…Nonetheless, there is some evidence to suggest that energetically expensive traits such as immunity can trade off against testis size and ejaculate quality (9,10), and across species of fruit flies in the genus Drosophila, species developing larger testes require longer periods of sexual maturation (11,12). Finally, a recent comparative study of bats revealed a trade-off between brain size and testes size, two metabolically expensive organs (13).…”

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confidence: 99%

Evolutionary trade-off between weapons and testes

Simmons

Emlen

2006

Proc. Natl. Acad. Sci. U.S.A.

277

255

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It has long been recognized that male mating competition is responsible for the evolution of weaponry for mate acquisition. However, when females mate with more than one male, competition between males can continue after mating in the form of sperm competition. Theory predicts that males should increase their investment in sperm production as sperm competition is increased, but it assumes that males face a trade-off between sperm production and other life-history traits such as mate acquisition. Here, we use a genus of horned beetle, Onthophagus, to examine the trade-off between investment in testes required for fertilizations and investment in weapons used to obtain matings. In a within-species study, we prevented males from developing horns and found that these males grew larger and invested relatively more in testes growth than did males allowed to grow horns. Among species, there was no general relationship between the relative sizes of horns and testes. However, the allometric slope of horn size on body size was negatively associated with the allometric slope of testes size on body size. We suggest that this reflects meaningful evolutionary changes in the developmental mechanisms regulating trait growth, specifically in the degree of nutrition-dependent phenotypic plasticity versus canalization of traits. Finally, we show how this resource allocation trade-off has influenced the evolutionary diversification of weapons, revealing a rich interplay between developmental trade-offs and both preand postmating mechanisms of sexual competition.secondary sexual traits ͉ sperm competition ͉ testes size ͉ beetle horns

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“…Such factors are likely to apply in a similar manner to all amniotes, potentially explaining the consistency in the average upper limit to the relative investment in testes mass as a proportion of body mass (as measured by percentage testes mass) between groupings with different allometric relationships, such as general amniotes (including reptiles, birds and mammals), marsupials, echolocating bats and cetaceans, despite the very large variations of body mass at which this limit is reached. However, its exact value in a given species will depend on the trade-off between the reproductive success provided by testes and the cost to other aspects of the body (e.g., [8]). In particular, when levels of sperm competition are high, the trade-off may result in a greater proportion of resources being allotted to testes tissue in order to ensure reproductive success, even at the cost of reduced survival, due to the decreased proportional use of resources for other functions [6,8,10].…”

Section: Resultsmentioning

confidence: 99%

“…In particular, when levels of sperm competition are high, the trade-off may result in a greater proportion of resources being allotted to testes tissue in order to ensure reproductive success, even at the cost of reduced survival, due to the decreased proportional use of resources for other functions [6,8,10]. In contrast, when it is low, the trade-off may be pushed in the opposite direction and select for relatively smaller tissues [6,8,10]. In either case, body mass will not be a factor in this trade-off, so it will be size independent.…”

Section: Resultsmentioning

confidence: 99%

“…In the past, testes mass allometry (TMA) was assumed to be a relatively simple, linear relationship when both body mass and testes mass are log-transformed (e.g., [6][7][8][9][10]), and most studies that have examined it have done so in order to control for allometry when studying the effects of other potential variables on relative investment in testes mass (e.g., [6][7][8][9][10]). However, recent research has revealed TMA in amniotes to be one of the most complex allometric relationships identified to date, both in terms of it general form (which is has a high level of consistency across many orders of birds, reptiles and mammals) and in terms of how it varies dramatically in a small number of taxonomically distinct groups [2,11].…”

Section: Introductionmentioning

confidence: 99%

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Exploring and Explaining Complex Allometric Relationships: A Case Study on Amniote Testes Mass Allometry

MacLeod

2014

Systems

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While many allometric relationships are relatively simple and linear (when both variables are log transformed), others are much more complex. This paper explores an example of a complex allometric relationship, that of testes mass allometry in amniotes, by breaking it down into linear components and using this exploration to help explain why this complexity exists. These linear components are two size-independent ones and a size-dependent one, and it is the variations in the interactions between them across different body mass ranges that create the complexity in the overall allometric relationship. While the size-independent limits do not vary between amniote groupings, the slope and the intercept of the size-dependent component does, and it is this that explains why some amniote groups conform to allometric relationships with apparently very different forms. Thus, breaking this complex allometric relationship down into linear components allows its complexity to be explored and explained, and similar processes may prove useful for investigating other complex allometric relationships. In addition, by identifying size-independent upper and lower limits to the proportional investment in specific structures, it allows the prediction of when allometric relationships will remain simple and linear; and when they are likely to develop higher levels of complexity.

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Mating system and brain size in bats

Cited by 162 publications

References 60 publications

Social fishes and single mothers: brain evolution in African cichlids

Social fishes and single mothers: brain evolution in African cichlids

Evolutionary trade-off between weapons and testes

Exploring and Explaining Complex Allometric Relationships: A Case Study on Amniote Testes Mass Allometry

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