Há alguns dias, me deparei com um interessante vídeo sobre os chamados “fósseis vivos”. O vídeo focou mais nos problemas de usá-los como argumentos contra a teoria da evolução, e aproveitei a oportunidade para falar mais sobre essas linhagens longevas.
‘Fóssil vivo‘ é um termo usado para descrever linhagens que acredita-se terem se originado há muito tempo e que mantêm características que se assemelham a seus parentes fósseis. Alguns exemplos bem conhecidos dessas linhagens são os Tuatara da Nova Zelândia (Sphenodon punctatus) e as árvores Gingkos (Gingko biloba).
A couple of days ago I came across a nice video (in Portuguese only, sorry) about so-called “living fossils”. The video focused on the problems of using them as arguments against evolution. But I’d like to take the opportunity to talk more about these long-lived lineages.
‘Living fossil’ is a term used to describe lineages that are thought to have been around for a very long time and retain characteristics that resemble of their fossil relatives. A couple of well-known examples of these lineages are the Tuatara of New Zealand (Sphenodon punctatus) and the Gingko tree (Gingko biloba).
The sending of letters under the pen name ‘St. Valentine’ began back in the middle ages as a way of communicating affection during the practice of courting. Fast forward to 2020 and Valentine’s Day is a day for celebrating romance, but now it typically features the exchange of gifts and cards between lovers.
Minimising the effects the ongoing Anthropocene mass extinction has become one of the main challenges of our era. The data suggest that the current rate of species loss is 100–1,000 greater than the background rates seen in the geological record. “But does it really matter if species are lost?” This question has permeated social and political debates. It’s usually used to demean conservation efforts. But it has also intrigued conservation scientists.
We know that species don’t occur alone in their environment. They’re entangled by their interactions, forming complex networks. In these networks the loss of one species may result in the loss of other species that depend on it. This process is known as co-extinction. Estimates of the magnitude of past and future extinction rates have often failed to account for the interdependence among species and the consequences of primary species loss on other species though. Continue reading →
Minimizar os efeitos do atual processo de extinção em massa do Antropoceno se tornou um dos principais desafios da nossa era. Os dados sugerem que a taxa atual de perda de espécies é 100-1.000 vezes maior do que as taxas de fundo observadas no registro geológico. “Mas realmente importa se uma espécie é perdida?” Essa questão que permeia os debates sociais e políticos, geralmente para desqualificar os esforços de conservação, também tem intrigado os cientistas da conservação.
Sabemos que as espécies não ocorrem sozinhas em seu ambiente. Elas estão interligadas por suas interações ecológicas, formando redes complexas. Nessas redes, a perda de uma espécie pode resultar em um efeito dominó, culminando na perda secundária de outras espécies. Esse processo é conhecido como co-extinção. As estimativas da magnitude das taxas de extinção passadas e futuras muitas vezes falharam em explicar a interdependência entre as espécies e as conseqüências da perda primaria de espécies. Continue reading →
Sequencing ultraconserved DNA for phylogenetic research is a hot topic in evolution right now. As the name implies, Ultraconserved Elements (UCEs) are regions of the genome that are nearly identical among distantly related organisms. They can provide useful information for difficult phylogenetic questions. The list of advantages is long – among others, UCEs are:
phylogenetically informative on different timescales.
A key reason for the method’s success is the developers’ commitment to full transparency, active tutoring, and willingness to help next-gen sequencing newbies like me to get started. Help is just a github-issue post away.
Five years ago at Evolution 2014, ‘The Dark Side of Phylogenetics’ symposium (organised by Natalie Cooper) explored some of the issues with phylogenetic comparative methods (PCMs). This year at Evolution 2019, Michael Landis and Rosana Zenil-Ferguson are organising a contrasting ‘Bright Side of Phylogenetics‘ spotlight session (featuring Michael Matschiner). They aim to promote research that has overcome these pitfalls and that explores innovations in phylogenetics. Clearly they found our lack of faith disturbing.
Natalie and Michael have created a Virtual Issue to complement the spotlight session: Phylogenetics and Comparative Methods: The Bright and Dark Sides. It highlights recent Methods in Ecology and Evolution papers that feature either the ‘Bright Side’ or ‘Dark Side’ of phylogenetics and comparative methods. This Virtual Issue also highlights the diversity of researchers around the world working on these exciting questions. We hope you have a good feeling about it! Continue reading →
The study of interactions and their impacts on communities is a fundamental part of ecology. Much work has been done on measuring the interactions between species and their impacts on relative abundances of species. Progress has been made in understanding of the interactions at the ecological level, but we know that co-evolution is important in shaping the structure of communities in terms of the species that live there and their characteristics. Continue reading →
Plant-pollinator interactions are often considered to be the textbook example of co-evolution. But specialised interactions between plants and pollinators are the exception, not the rule. Plants tend to be visited by many different putative pollinator species, and pollinating insects tend to visit many plant hosts. This means that diffuse co-evolution is a much more likely driver of speciation in these communities. So, the standard phylogenetic methods for evaluating co-evolution aren’t applicable in most plant-pollinator interactions. Also, many plant-pollinator communities involve insect species for which we do not yet have fully resolved phylogenies. Continue reading →
In our recent publication (Rabosky et al. 2018) we assembled a huge phylogeny of ray-finned fishes: the most comprehensive to date! While all of our data are accessible via Dryad, we felt like we could go the extra mile to make it easy to repurpose and reuse our work. I’m pleased to report that this effort has resulted in two resources for the community: the Fish Tree of Life website, and the fishtree R package. The package is available on CRAN now, and you can install it with:
The source is on GitHub in the repository jonchang/fishtree. The manuscript describing these resources has been published in Methods in Ecology and Evolution (Chang et al. 2019).