Developmental differences are correlated with relative brain size in birds: a comparative analysis

Iwaniuk, Andrew N.; Nelson, Jacob L.

doi:10.1139/z03-190

Cited by 176 publications

(238 citation statements)

References 39 publications

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“…Relative brain sizes were obtained from the data from Iwaniuk & Nelson [25] and Mlíkovský [26]. See electronic supplementary material, appendix S2, for more information and the raw data.…”

Section: Methodsmentioning

confidence: 99%

Can traits predict species' vulnerability? A test with farmland passerines in two continents

Pocock

2010

Proc. R. Soc. B.

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Species' traits have been used both to explain and, increasingly, to predict species' vulnerability. Trait-based comparative analyses allow mechanisms causing vulnerability to be inferred and, ideally, conservation effort to be focused efficiently and effectively. However, empirical evidence of the predictive ability of trait-based approaches is largely wanting. I tested the predictive power of trait-based analyses on geographically replicated datasets of farmland bird population trends. I related the traits of farmland passerines with their long-term trends in abundance (an assessment of their response to agricultural intensification) in eight regions in two continents. These analyses successfully identified explanatory relationships in the regions, specifically: species faring badly tended to be medium-sized, had relatively short incubation and fledging periods, were longer distant migrants, had small relative brain sizes and were farmland specialists. Despite this, the models had poor ability to predict species' vulnerability in one region from trait-population trend relationships from a different region. In many cases, the explained variation was low (median R 2 ¼ 8%). The low predictive ability of trait-based analyses must therefore be considered if such trait-based models are used to inform conservation priorities.

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Section: Methodsmentioning

confidence: 99%

Can traits predict species' vulnerability? A test with farmland passerines in two continents

Pocock

2010

Proc. R. Soc. B.

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“…What about birds? Although birds do not possess absolute brain sizes anywhere in the region of most mammals (mean 3.38G0.11 g; range from 0.13 (Cuban Emerald hummingbird) to 46.19 g (Emperor penguin; Iwaniuk & Nelson 2003) compared with the 7800 g brain of a sperm whale), some birds have brains that, relatively speaking, are the same size as those of chimpanzees (after removing the effects of body size; Emery & Clayton 2004).…”

Section: The Avian Social Brain?mentioning

confidence: 99%

“…Such diversity within a species cannot easily be represented in an analysis of group size and brain size. Therefore, the relationship between brain size and mating system was investigated using the same brain volume dataset as above (Iwaniuk & Nelson 2003). Birds were classified according to whether they were monogamous, cooperative breeders, polygamous, polygynous or polyandrous.…”

Section: Mating System Brains and Social Complexitymentioning

confidence: 99%

Cognitive adaptations of social bonding in birds

Emery

Seed

Bayern

et al. 2007

Phil. Trans. R. Soc. B

347

341

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The ‘social intelligence hypothesis’ was originally conceived to explain how primates may have evolved their superior intellect and large brains when compared with other animals. Although some birds such as corvids may be intellectually comparable to apes, the same relationship between sociality and brain size seen in primates has not been found for birds, possibly suggesting a role for other non-social factors. But bird sociality is different from primate sociality. Most monkeys and apes form stable groups, whereas most birds are monogamous, and only form large flocks outside of the breeding season. Some birds form lifelong pair bonds and these species tend to have the largest brains relative to body size. Some of these species are known for their intellectual abilities (e.g. corvids and parrots), while others are not (e.g. geese and albatrosses). Although socio-ecological factors may explain some of the differences in brain size and intelligence between corvids/parrots and geese/albatrosses, we predict that the type and quality of the bonded relationship is also critical. Indeed, we present empirical evidence that rook and jackdaw partnerships resemble primate and dolphin alliances. Although social interactions within a pair may seem simple on the surface, we argue that cognition may play an important role in the maintenance of long-term relationships, something we name as ‘relationship intelligence’.

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“…For flight timing, we noted both the age of first flight and the age of first 'sustained flight.' Because timing of first flight was not available for all species in this series, we additionally took data on flight timing from Iwaniuk and Nelson (2003). For some species, flight timing data was available from more than one source.…”

Section: Measurements Of Museum Specimens: Shorebirds and Warblersmentioning

confidence: 99%

Life history as a constraint on plasticity: developmental timing is correlated with phenotypic variation in birds

2015

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Understanding why organisms vary in developmental plasticity has implications for predicting population responses to changing environments and the maintenance of intraspecific variation. The epiphenotype hypothesis posits that the timing of development can constrain plasticity-the earlier alternate phenotypes begin to develop, the greater the difference that can result amongst the final traits. This research extends this idea by considering how life history timing shapes the opportunity for the environment to influence trait development. We test the prediction that the earlier an individual begins to actively interact with and explore their environment, the greater the opportunity for plasticity and thus variation in foraging traits. This research focuses on life history variation across four groups of birds using museum specimens and measurements from the literature. We reasoned that greater phenotypic plasticity, through either environmental effects or genotype-by-environment interactions in development, would be manifest in larger trait ranges (bills and tarsi) within species. Among shorebirds and ducks, we found that species with relatively shorter incubation times tended to show greater phenotypic variation. Across warblers and sparrows, we found little support linking timing of flight and trait variation. Overall, our results also suggest a pattern between body size and trait variation, consistent with constraints on egg size that might result in larger species having more environmental influences on development. Taken together, our results provide some support for the hypothesis that variation in life histories affects how the environment shapes development, through either the expression of plasticity or the release of cryptic genetic variation.

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Developmental differences are correlated with relative brain size in birds: a comparative analysis

Cited by 176 publications

References 39 publications

Can traits predict species' vulnerability? A test with farmland passerines in two continents

Can traits predict species' vulnerability? A test with farmland passerines in two continents

Cognitive adaptations of social bonding in birds

Life history as a constraint on plasticity: developmental timing is correlated with phenotypic variation in birds

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