Creationism in Crisis - Increased Complexity Does Not Always Mean Increased Diversity

Songbirds and passerines have less complex skeletons and are species rich

Credit: nataba

Study shows birds that have evolved greater complexity are less biodiverse

Flamingoes and geese
High skeletal complexity, low species diversity

The creation cult has fooled its members into believing that evolution, as defined by science, always involves increasing complexity. They do this because it's easier then to argue that either greater complexity implies intelligent design because systems become 'irreducibly complex' or because it implies that science is claiming that new structures can arise by evolution which contravenes some half-baked notion about new information contravening the second law of thermodynamics by equating 'information' to energy in a closed system.

This claim is blatantly untrue, of course, as any study of parasites will show, since parasites normally evolve by loss of complexity and genetic information, as I reported recently, and repeatedly point out in my illustrated book, The Malevolent Designer: Why Nature's God is not Good, which, judging by the misleading, lying and hysterical 'reviews' on Amazon is still causing panic in the creationist cult.

If that claim of increasing complexity leading to increased structures were true, we would expect it to always lead to increased biodiversity, which is exactly what we often see, but the truth is not as black and white as creationist frauds need to present it to their simplistic dupes.

As a new study by researchers at the Milner Centre for Evolution at the University of Bath have shown, in birds, evolution often results in less diversity and greater specialisation, as species adapt to new niche opportunities or environmental change. Their findings are published, open access, in Nature Communications.

As the press release from Bath University explains:

Study shows birds that have evolved greater complexity are less biodiverse

Research from the Milner Centre for Evolution shows that birds with more complex skeletons are more specialised and so are less species rich.

A new study of the evolution of birds shows that as their skeletons become more complex, they also decrease in diversity, with fewer species as they become more specialised in their niches. The findings, published in Nature Communications, show a correlation between skeleton complexity and bird diversity for the first time, and help biologists better understand why biodiversity varies across the birds.

Researchers at the Milner Centre for Evolution at the University of Bath looked at 983 species across all major groups of living birds and measured the complexity of their skeletons by comparing the bones in their fore limbs (wings) and hind limbs (legs).

They found that less complex birds - those with a smaller differences between their fore and hind limbs - had more species diversity than those with higher complexity and a larger difference between their limbs.

For example, birds such as pigeons, gulls and songbirds (passerines) have low skeletal complexity but a high diversity of species living in varied habitats across the world.

At the other end of the spectrum, flamingos, and ostriches have short wings in comparison to their legs, and so have more complex limb skeletons. Groups with more complex skeletons may occupy smaller niches and are less able to subdivide those niche spaces in order to produce new species.

Whilst evolution can produce forms with lower complexity, these findings suggest that birds with more complex skeletons have become more specialised over time and so more developmentally entrenched. This may make them less likely to evolve back to become simpler again.

Causes of biodiversity

Professor Matthew Wills, from the Milner Centre for Evolution at the University of Bath, said:

We wanted to understand what causes some groups of birds to be species rich and others to be species poor – although ecology obviously plays an important part, it doesn’t account for the huge differences we see in biodiversity.

The received wisdom that there is no direction to evolution - that selection can act in any direction. Our study suggests that, in birds at least, the more they specialise, the less they are able to give rise to new species.

Putting all the eggs in one basket

The researchers also found that birds with more complex skeletons were generally more ecologically specialised, occupying fewer habitats and foraging for food in fewer ways.

Andrew Brinkworth, PhD student at the Milner Centre for Evolution and first author of the paper, said:

Species can evolve to be specialised, and fill very small niches. However in doing so, they restrict the number of routes they can evolve further, meaning they are likely to be less resilient to changes in the environment such as those caused by habitat loss, disruption to food chains and climate change.

From our findings we predict that birds with more complex skeletons and less diversity will be at greater risk of extinction from these changes.

The researchers next plan to test if this pattern is also true in other animals. The study was led by the University of Bath, in collaboration with colleagues at the University of Lincoln, University College London and the Chinese Academy of Sciences.

Abstract

Species richness is strikingly uneven across taxonomic groups at all hierarchical levels, but the reasons for this heterogeneity are poorly understood. It is well established that morphological diversity (disparity) is decoupled from taxonomic diversity, both between clades and across geological time. Morphological complexity has been much less studied, but there is theory linking complexity with differential diversity across groups. Here we devise an index of complexity from the differentiation of the fore and hind limb pairs for a sample of 983 species of extant birds. We test the null hypothesis that this index of morphological complexity is uncorrelated with clade diversity, revealing a significant and negative correlation between the species richness of clades and the mean morphological complexity of those clades. Further, we find that more complex clades tend to occupy a smaller number of dietary and habitat niches, and that this proxy for greater ecological specialisation correlates with lower species richness. Greater morphological complexity in the appendicular skeleton therefore appears to hinder the generation and maintenance of species diversity. This may result from entrenchment into morphologies and ecologies that are less capable of yielding further diversity.

Brinkworth, A., Green, E., Li, Y. et al.
Bird clades with less complex appendicular skeletons tend to have higher species richness.
Nat Commun 14, 5817 (2023). https://doi.org/10.1038/s41467-023-41415-2

Copyright: © [year] The authors.
Published by [publisher]. Open access
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Note the complete dependence of the scientists on the Theory of Evolution by Natural selection to explain these observations, especially where specialisation for particular niches involves greater complexity as part of the adaptive process. The explanation is that this then reduces the opportunities for further diversification, either because the specialised morphology can't diversify further or because the narrowness of the niche doesn't generate any environmental pressure for diversity, or both.

Two of the authors of this study, Marcello Ruta & Matthew A. Wills have also written an article in The Conversation, drawing on these findings to make some general points about evolution in general and human evolution in particular. This will be the subject of my next blog post.

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