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Study Links Brain Development to Size Differences in Mammals
Research led by the University of Bath suggests a correlation between the degree of sexual size dimorphism (SSD) in mammals and the development of brain functions. Findings have been published in the scientific journal Nature Communications.
Sexual size dimorphism is a phenomenon where males and females of a species exhibit different sizes. For instance, male elephant seals can weigh up to three times more than their female counterparts. Conversely, species like dolphins show no size disparity between sexes. Humans are intermediaries, as males are generally larger but there exists significant overlap in size within the population.
The researchers, part of the Milner Center for Evolution, analyzed the genetic make-up of 124 mammal species to explore how SSD relates to evolutionary trends in the genome. They categorized genes into families based on their functions and examined the size of these families.
The study discovered that species with pronounced size differences displayed larger gene families associated with olfactory functions (smell) while having smaller gene families linked to brain development. This contrasts with species where males and females are similar in size, which tend to have expanded gene families related to brain development.
According to the study, the emphasis on olfactory traits in species with significant size differences may enhance their abilities in mate and territory selection. On the other hand, mammals with less pronounced SSD are suggested to prioritize brain evolution, fostering more complex social interactions where size is not the primary factor in mate selection.
Key Insights from the Research
Dr. Benjamin Padilla-Morales, who led the study, expressed surprise at the strong correlation between significant SSD and enlarged gene families for olfactory capabilities. He noted, “Interestingly, we found that the gene families that were smaller in size were associated with brain development.”
Dr. Padilla-Morales further explained, “This suggests that species exhibiting minimal SSD may have enhanced brain functionality, contributing to advanced behaviors such as monogamous pair bonding and shared parental care.” He emphasized that while physical size can be a major factor in sexual selection for some mammals, it is less influential in others.
This research prompts further inquiry into how characteristics like SSD may influence the evolution of cognitive abilities and genetic diversity among mammals. Future studies aim to delve into how variations in testis size may also play a role in the evolution of mammalian genomes.
More information: Benjamin Padilla-Morales et al, Sexual size dimorphism in mammals is associated with changes in the size of gene families related to brain development, Nature Communications (2024).
Source
phys.org