Examining divergence within a species complex of flying lizards

credit: BBC's Planet Earth 2

Southeast Asia is home to some of the coolest creatures on Earth: the flying dragons (genus Draco). The gliding ability of these Agamid lizards make them unique among all vertebrates. Unlike other flyers/gliders, Draco's "wings" (patagia) are attached to ribs which can be extended voluntarily for either gliding or communication.

Draco Gif
credit: BBC's Planet Earth 2
Draco Map

The spotted flying lizard (Draco maculatus) is currently recognized as a single species, but we hypothesize that multiple species are hidden under this single taxonomic name in a species complex. Large geographic ranges and distinct morphological differences within a taxon recognized as a "single species" can be indicators of a species complex, and D. maculatus possesses both of these characteristics (see map above).

We sequenced six genetic regions and assessed the degree of divergence within D. maculatus using maximum likelihood and Bayes factor delimitation. Our findings allude to potential forces driving speciation within Indochina and indicate that species-level divergence is present within this group (see poster for study details).

The powerhouse of asexual collapse?

Why share offspring with a mate?

Tesselatus Head Shot

As a casual observer of life on earth, you may have noticed that many creatures reproduce by having sex. Because so many organisms "have sex", many people haven't even considered an alternative used for passing genes to offspring. However, evolutionary biologists like to make observations and then ask the questions. As for sex, why have it?

Early Life

Sex is costly. From a biological perspective, the "purpose of life" is to pass as much of "you" into the future as is possible. Nearly all animals forfeit passing on half of their genetic material for a sexual partner; offspring are made up of ~50% dad's DNA and ~50% mom's DNA. This means if something only has one child, half of their genes hit a dead end. However, sexual organisms with one child do not send half of their genes to the grave, because 100% of their DNA is passed on to offspring (see diagram above).

Another problem if you're a sexual organism is that you have to:

  • Find an individual of the opposite sex
  • Convince them to mate with you
  • Be careful not to get eaten by something while mating
  • Potentially deal with sexually transmitted disease

    So back to our question: If sex kind of sucks, why have it? Well, to address that question it may be appropriate to ask another: Asexual reproduction sounds nice, but what's the catch? This is a major question within evolutionary biology that I am seeking to address using southwestern whiptail lizards (genus: Aspidoscelis) as a model system. One third of this genus of 40+ species reproduces via parthenogenesis (a form of asexual reproduction wherein no male input WHATSOEVER is needed).