Evolution

Though the largest Sperm whales weigh up to 50 tons and and the smallest bat barely reaches a gram, they share something in common.

They both use echolocation, biological sonar, for hunting.

Echolocation systems are one of nature's most successful specializations. About 1,100 species of bats and roughly 80 species of toothed whales use the technique – that's 25% of all mammals. But why did such different animals as whales and bats evolve the same technique? It isn't biological kinship, bats and whales are no closer related to each other than all the other mammals that descended from the land vertebrates around 200 million years ago.


Pigs, jellyfish and zebrafish don't seem to have much in common with each other, much less humans, but the different species are all pieces of a puzzle which is helping to solve the riddles of diseases in humans - like hereditary forms of diseases affecting the nervous system, such as Parkinson's disease, Alzheimer's disease, autism, epilepsy and the motor neurone disease ALS. 

In a new project, Aarhus University scientists focused on a specific gene in pigs. The gene, SYN1, encodes the protein synapsin, which is involved in communication between nerve cells. Synapsin almost exclusively occurs in nerve cells in the brain. Parts of the gene can thus be used to control an expression of genes connected to hereditary versions of the aforementioned disorders.


A new study has revealed that the ancestors of chelicerates (spiders, scorpions, etc.) branched off from the family tree of other arthropods, such as including insects, crustaceans and millipedes, more than half a billion years ago.


Bees are more genetically related to ants than they are to social wasps such as yellow jackets and paper wasps, according to a new paper.

 Ants, bees and stinging wasps all belong to the aculeate (stinging) Hymenoptera clade, the insect group in which social behavior is most extensively developed, said senior author and ant specialist Phil Ward, professor of entomology at UC Davis. 

The use of genome sequencing and bioinformatics answers a piece of a long-standing, unanswered evolutionary puzzle. Previously it was thought that ants and bees were distantly related, with ants being closer to certain parasitoid wasps.


The great angiosperm radiation of the mid-Cretaceous, the dramatic explosion of flowering plant species that occurred about 100 million years ago, is thought to have been good news for evolving mammals, providing them with new options for food and habitat. 

Previous literature suggested the spread of angiosperms, along with the evolution of pollinating insects, may have spurred an increase in the diversity of mammals. The idea made sense: The radiation would likely have resulted in more food sources from seeds, fruits, leaves and insects.

Not always. 


Before there was life on Earth, there was a primordial soup of molecules, and at some point a specialized molecules began replicating. This self-replication kick-started a biochemical process that would lead to the first organisms.

How those molecules began replicating has been one of science's enduring mysteries.

In the early 1980s, researchers found that ribozymes — RNA enzymes — act as catalysts. It was evidence that RNA can be both the blueprints and the chemical catalysts that put those blueprints into action. This finding led to the "RNA World" hypothesis, which posits that RNA alone triggered the rise of life from a sea of molecules.


A genetic phenomenon that allows for the selection of multiple genetic mutations that all lead to a similar outcome - a 'soft selective sweep' such as the ability to digest milk- has been characterized for the first time in humans.

This soft selective sweep was described in the population of Ethiopia by a team of geneticists from University College London, University of Addis Ababa and Roskilde University and reveals that individuals from the Eastern African population have adapted to be able to digest milk, but via different mutations in their genetic material.


The ancient closest relatives of mammals, the cynodont therapsids, not only survived the greatest mass extinction of all time 252 million years ago, they thrived in the aftermath.

The first mammals arose in the Triassic period, more than 225 million years ago. These early fur balls include small shrew-like animals such as Morganucodon from England, Megazostrodon from South Africa and Bienotherium from China.  They had differentiated teeth - incisors, canines, molars - and large brains and were probably warm-blooded and covered in fur; all characteristics that stand them apart from their reptile ancestors, and which contribute to their huge success today.

Females select the 'right' sperm to fertilize their eggs when faced with the risk of being fertilized by wrong sperm from a different species and researchers recently set out to investigate salmon and trout, which fertilize externally in river water, because the two species occasionally hybridize in the wild.

Since hybrid offspring become reproductive dead-ends, females of both species are under selection to avoid hybrid fertilizations, and instead promote external fertilization by their own species' sperm.


Two papers published this week have proposed explanations regarding the evolution of social monogamy among mammals and especially primates.  Of three competing hypothesis, one proposes that a driving force in establishing social monogamy was the protection of offspring by preventing male infanticide, while the other proposes that social monogamy is the result of female intolerance towards each other and a low population density that simply prevents males from adequately "guarding" females from other males (1).