Tree of Life, new research needed


This 19 February 2020 video says about itself:

The Tree of Life Is Messed Up

Taxonomy is a powerful tool, and one that modern biology wouldn’t be able to function without. But trying to shoehorn the messy, complicated web of interrelationships that is biology into neat boxes has resulted in a pretty messy tree of life.

Hosted by: Olivia Gordon

Darwin’s finches evolution, new research


This 2017 video says about itself:

Evolution by Natural Selection – Darwin’s Finches | Evolution | Biology

In December 1831 a naturalist called Charles Darwin boarded the HMS Beagle, bound on a surveying voyage of South America. Whilst the ship and crew carried out coastline surveys, Darwin was free to explore the islands en route. In 1835 the Beagle arrived at the Galapagos islands, near Ecuador. What Darwin found there surprised him greatly. As well as giant tortoises and marine iguanas, Darwin collected and preserved a variety of different songbirds called finches. Upon returning to the UK he examined them together with ornithologist John Gould, and made some fascinating discoveries.

From the University of Bristol in England:

How the development of skulls and beaks made Darwin’s finches one of the most diverse species

February 3, 2020

Darwin’s finches are among the most celebrated examples of adaptive radiation in the evolution of modern vertebrates and now a new study, led by scientists from the University of Bristol, has provided fresh insights into their rapid development and evolutionary success.

Study of the finches has been relevant since the journeys of the HMS Beagle in the 18th century which catalysed some of the first ideas about natural selection in the mind of a young Charles Darwin.

Despite many years of research which has led to a detailed understanding of the biology of these perching birds, including impressive decades-long studies in natural populations, there are still unanswered questions.

Specifically, the factors explaining why this particular group of birds evolved to be much more diverse in species and shapes than other birds evolving alongside them in Galapagos and Cocos islands have remained largely unknown.

A similar phenomenon is that of the honeycreepers endemic to the Hawaiian archipelago. These true finches (unlike Darwin’s finches which are finch-like birds belonging to a different family) radiated to achieve an order of magnitude more in species and shapes than the rest of the birds inhabiting those islands.

An international team of researchers from the UK and Spain tackled the question of why the rapid evolution in these birds from a different perspective.

They showed in their study published today in the journal Nature Ecology & Evolution that one of the key factors related to the evolutionary success of Darwin’s finches and Hawaiian honeycreepers might lie in how their beaks and skulls evolved.

Previous studies have demonstrated a tight link between the shapes and sizes of the beak and the feeding habits in both groups, which suggests that adaptation by natural selection to the different feeding resources available at the islands may have been one of the main processes driving their explosive evolution.

Furthermore, changes in beak size and shape have been observed in natural populations of Darwin’s finches as a response to variations in feeding resources, strengthening these views.

However, recent studies on other groups of birds, some of which stem from the previous recent research of the team, have suggested that this strong match between beak and cranial morphology and ecology might not be pervasive in all birds.

Professor Emily Rayfield, from the University of Bristol’s School of Earth Sciences, co-authored the new study. She said: “Other factors such as constraints on skull shape during development, the use of the beak for many other functions and the fact that the skull and beak develop and function as a coherent unit may have contributed to this mismatch.

“Therefore, the strong connection between beak, cranial morphology and feeding ecology over the evolution of Darwin’s finches, Hawaiian honeycreepers, and perhaps other lineages of birds, might have been only possible if this tight coevolution of cranial regions is somehow ‘relaxed’ and those regions are able to evolve more freely.”

Lead author Guillermo Navalón, recently graduated from a PhD at the University of Bristol and now a Postdoctoral Researcher at the University of Oxford, added: “By taking a broad scale, numerical approach at more than 400 species of landbirds (the group that encompasses all perching birds and many other lineages such as parrots, kingfishers, hornbills, eagles, vultures, owls and many others) we found that the beaks of Darwin’s finches and Hawaiian honeycreepers evolved in a stronger association with the rest of the skull than in most of the other lineages of landbirds.

“In other words, in these groups the beak is less independent in evolutionary terms than in most other landbirds.”

Jesús Marugán-Lobón co-author of the study and Lecturer at the Autonomous University of Madrid, said: “We found that as a result of this stronger cranial integration, these birds could evolve in a more versatile way but mostly constrained along a very specific direction of adaptive change in the shape of their skulls.

“Paradoxically, we hypothesised that this allowed them to evolve many different shapes very rapidly, filling many of the available niches in their archipelagos as a result.”

In contrast, the authors asserted that the other sympatric bird lineages that occupied the island archipelagos at similar time to the ancestors of finches and honeycreepers all belong to the group with the lowest cranial integration in their study and suggest that this was a limiting factor for rapid evolution in other lineages.

Guillermo Navalón added: “While these results are exciting, this is mainly the work of my PhD and at the minute we are working on solving different unanswered questions that stem from this research.

“For instance, are these evolutionary situations isolated phenomena in these two archipelagos or have those been more common in the evolution of island or continental bird communities? Do these patterns characterise other adaptive radiations in birds?

“Future research will likely solve at least some of these mysteries, bringing us one step closer to understanding better the evolution of the wonderful diversity of shapes in birds.”

Butterflies’ smell and evolution, new research


This 2010 video says about itself:

Bicyclus anynana: male and female butterflies performing courtship behavior

From the National University of Singapore:

Butterflies can acquire new scent preferences and pass these on to their offspring

February 3, 2020

Summary: New studies demonstrate that insects can learn from their previous experiences and adjust their future behavior for survival and reproduction.

It was long believed that physical characteristics acquired by organisms during their lifetime could not be passed on to their offspring. However, in recent years, the theory of inheritance of acquired traits has gained support, with studies showing how offspring of rats and tiny worms inherit behaviours that were acquired by their parents in response to particular environmental stimuli, even when the stimulus is no longer present in the offspring’s generation.

This theory is further supported by recent studies conducted by researchers from the National University of Singapore (NUS), in which they found that the inheritance of acquired traits also happens in butterflies, especially in the bush brown butterfly Bicyclus anynana.

Two research teams supervised by Associate Professor Antónia Monteiro, who is from the Department of Biological Sciences at the NUS Faculty of Science, as well as from Yale-NUS College, showed that both Bicyclus anynana caterpillars and adult butterflies can learn to prefer new odours if they are exposed to them during their development or early in life. The researchers also found that the offspring of the exposed caterpillars and butterflies show the same new preferences as their parents, even though they were not exposed themselves, indicating that their parents have passed their new acquired preferences to their children.

The findings of the two studies were published online in the scientific journals Evolution in October 2019 and Nature Communications in January 2020.

Learning to like new odours for feeding and mating

In the study that was published in Evolution, NUS doctoral student Ms V. Gowri, research fellow Dr Emilie Dion, and their collaborators exposed caterpillars and butterflies to new odours they typically do not experience in their natural environment. In the experiments, caterpillars were fed with corn leaves — their usual food — coated with banana or with mango essence throughout their development. Most of these caterpillars preferred to eat leaves with the fruit essence after only a few days of exposure.

In the second study, which was published in Nature Communications, Dr Dion and her collaborators exposed young female butterflies to new sex pheromone blends, a perfume produced by males to entice females to mate with them. The results showed that the exposed females later preferred to mate with males having the new pheromone blend.

“These results are significant because they show that insects are not only driven by their instincts, but can also learn from their previous experience and adjust their future behaviour accordingly. The consequences of their learning abilities on their survival and reproduction can be very important,” shared Dr Dion.

Offspring acquired the learned preferences of their parents

Both studies examined the behaviour of the offspring of the exposed Bicyclus anynana caterpillars and butterflies. The results revealed that the new generation also exhibited the same preference for the new food odours, or the new sex pheromone blends, although they were never exposed to these odours themselves. The teams concluded that the offspring inherited the preferences acquired by their parents.

While these learning and inheritance processes are hypothesised to facilitate the evolution of diet diversity across insects, and mate selection over the course of insect diversification, the impact of this inheritance mechanism on evolution is still unknown.

“We are now investigating whether this behavioural transmission is maintained for more than one generation, and also probing the underlying molecular mechanisms in our model species, as these remain some of the most exciting unanswered questions in the field of evolutionary biology,” said Assoc Prof Monteiro.

The study reveals that the African satyrid butterfly Bicyclus anynana (B. anynana), a member of the sub-family of the nymphalidae (or ‘brush-footed’) butterflies, changes its eyespot size using a complex physiological and molecular response that evolved gradually over millions of years. The findings also highlight that while temperature modulates hormone levels in various species of satyrid butterfly, B. anynana is just one of a few that take advantage of this response to regulate eyespot size: here.