Maternal care as a provider of adaptive behavioural, neural, and morphological diversity
Adaptive evolution is often described as a process whereby variation is targeted by natural selection to cause genetic change over time. Variation is therefore fundamental and required for selection to have an effect. While we often assume variation to have a heritable genetic basis this could represent an oversimplification1.
Variation can arise from a range of mechanisms, however this project will focus on the contribution of maternal influences on offspring, and how this contributes toward the variation found in a major adaptive radiation. Specifically, this project will use the exemplar adaptive radiation of African cichlids from Lake Malawi as a model to test the impacts of maternal care on behavioural, neural, and morphological diversity. Over 500 species of Malawi cichlids are known to exist, representing the largest extant example of an adaptive radiation. Cichlids are renown for the large amounts of phenotypic variation they display in craniofacial traits, and brain anatomy2,3. The vast majority of these species use mouthbrooding, whereby females incubate eggs and care for larvae within their buccal cavity. This is a reproductive tactic that is thought to increase survivorship as offspring can avoid predation, and emerge at a far more developed state than would be possible through other modes of fish parental care.
However, our preliminary data suggests that cichlid offspring phenotypes depend on differences among mothers in the mouthbrooding tactic. This includes influences on behaviour, morphology, and brain development. In this system, we can experimentally manipulate the duration of parental care, and hence investigate its role in determining offspring phenotype. Therefore, using a range of Malawi cichlid species the successful candidate will aim to assess the following questions:
1) What impact does mouthbrooding incur on social behaviours in cichlids, and does this reflect species differences?
2) How strongly can morphological variation be impacted by mouthbrooding across species and does this impact the function of trophic morphology?
3) What are the impacts of mouthbrooding on brain development and gene expression, and do these impacts last throughout ontogeny to adulthood?
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A Malawi cichlid performing maternal care through mouthbrooding