Two studies on reproduction in reptiles have made me go “wow, thats cool” this week. Read the rest of this entry »
Gene duplication is a major source of genomic novelty for evolution to work on. When genes duplicate, the extra copy of the gene is often redundant – it might degrade and become a pseudogene or take on a completely new function. Alternatively, the function of the original gene might become partitioned between the two duplicates in a process known as subfunctionalization. An excellent example of this has recently been reported in the genes that control male and female organ development in the flower, and it’s (almost) all down to a single amino acid change between the duplicate genes.
Development of male and female reproductive organs in flowers is controlled largely by a group of genes called MADS-box transcription factors. Different versions of these transcription factors (known as A, B or C function genes) are expressed in different parts of the developing flower, acting either alone or together to produce sepals, petals, stamens (male) or carpels (female)*.
Much of what we know about flower development comes from studies on two “model” plants – Arabidopsis (rockcress) and Antirrhinum (snapdragon). In these species, and in many other flowering plants, the MADs-box C-function gene that controls the production of carpels vs stamens has duplicated. In Arabidopsis, one of the copies (called AG) makes both male and female organs, but the other copy has taken on the completely new function of making seed pods shatter (and is appropriately called SHATTERPROOF). However, in Antirrhinum both copies still play a role in sex organ development: one copy (called FAR) makes only male parts, while the other copy (PLE) makes mainly female parts but also has a small role in making male parts.
Thus in Antirrhinum, the function of the original gene (making both male and female parts) has almost been split between the two duplicate copies. In a study published online in PNAS last week, researchers at the University of Leeds, led by Professor Brendan Davies, found a surprisingly simple difference in the two copies has led to their profoundly different roles. Read the rest of this entry »
As you might expect from an animal that is so evolutionarily distant from its nearest relatives, the tuatara also has some unique parasites to call its own. One of these is the tick Amblyomma sphenodonti (sometimes also called Aponomma sphenodonti), pictured here.
Like many ticks, A. sphenodonti are host-specific, spending all three of their life stages feeding on tuatara but dropping off into the soil in between stages.
So why should you care about tuatara ticks? Well, these ticks are evolutionarily distinct in their own right, and are actually quite rare – far rarer than the tuatara themselves. Read the rest of this entry »
I haven’t had much time for writing this week, so instead I thought I’d share this photo as a reminder to my New Zealand readers that it is actually spring, even though it doesn’t feel like it!
No, not for your local government (you’re too late for that). For New Zealand’s Bird of the Year, of course! Apparently the pukeko is out in front. Come on people, can’t we at least chose something endemic? A species that we don’t share with Australia and numerous other countries?? There’s plenty to chose from – the kakariki is giving the pukeko a run for its money (only 2 votes in it at 10am this morning!), and the old favorites kiwi, kakapo and weka might get up with a late run of voting. You can vote here.
Tuatara like it cold. Unusually so, for a reptile. While reptiles in most other countries are happiest with temperatures over 25 degrees celcius, here in New Zealand our reptiles prefer much lower temperatures. Alison Cree’s group at the University of Otago has been investigating exactly which temperatures tuatara prefer, with a view to determining whether new populations of tuatara could be established in the southern South Island.
This video has been doing the rounds, and its so cool I just have to post it here. The video shows the amazing maneuverability and speed of birds of prey in flight, thanks to “on bird” cameras mounted on a peregrine falcon and a goshawk.
hat-tip: Ars technica