Comparative Cryptobiosis
Cryptobiosis is an adaptation that some plants, animals and microbes exhibit whereby they enter a reversible near-ametabolic state in order to survive adverse environmental conditions such as desiccation or temperature extremes. In the Pienaar lab, we are culturing various bryophyte species, along with the tardigrades, rotifers and nematodes typically associated with these miniature plants. All of these organisms contain examples of cryptobiotic species and we are interested in quantifying the degree to which these organisms are cryptobiotic, the nature of this trait, variation in this trait, and why such variation exists. We use a combination of genomic, transcriptomic, phenomic and experimental microscopic techniques to get at this question. Ultimately we are interested in comparing this trait across tardigrades, bryophytes, rotifers and nematodes (deep evolutionary time) in order to understand the general mechanisms and evolution of this fascinating trait.
Supported by NSF CAREER Award (2045035) and UA ORED Award |
Fig Wasp Sex and Male Morph Allocation
Fig wasps, some of which pollinate fig trees and are famous for their quantifiable sex ratio biases that closely match LMC predictions, and others that parasitize this co-evolving mutualism are famous for the extreme male dimorphic forms they exhibit. My PhD thesis research focused on game theoretical modeling to understand the proximate and ultimate mechanisms underlying extreme male dimorphic forms in non-pollinating fig wasps. The data to test these modeling predictions come from various non pollinating fig wasp species in Southern Africa. The Otitesella sp. shown left are particularly interesting, where the large morph male (known as the Religiosa morph) use their oversized mandibles to decapitate conspecific males whilst competing for mating opportunities. The smaller male morph (shown left) disperses out of the fig, and uses the swollen black sack like structures on its feet to attract presumably unmated females for mating outside of the fig syconium.
Supported by UA CARSCA Award |
Phylogenetic Comparative Method Development
Euplectes weaver birds, represented on a conceptual macroevolutionary adaptive landscape where ridges represent optima for trade-offs between patch-size (red, orange, yellow) and tail length and the phylogeny reminds us that inheritance from common ancestors also plays a role in current trait values
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Ever since working in Thomas Hansen's lab as a post doc, I have become enthralled with the phylogenetic comparative method and what it can teach us about generalities in biology. In a long term collaboration with Thomas Hansen, Kzrysztof Bartozek, Jesualdo Fuentes Gonzalez and others, we continue to develop comparative methods based on processes that are compatible with trait adaptation over macro evolutionary time scales. We also use these methods on a variety of organisms, and in the process get to learn about so many different biological systems and collaborate with a variety of specialists for organisms and traits ranging through plant genomes, fish body shapes, lizard thermobiology, bird tail lengths and patch sizes, primate brain sizes and so on. The figure on the left, for example, depicts a macroevolutionary trade-off study between tail lengths with carotenoid patch sizes as sexual selection signals in Euplectes birds (in collaboration with Staffan Andersson at the University of Gothenburg, Sweden)
Supported by NSF CAREER award (2045035) |