Research

Bio-geo synthesis

The underlying biological processes cannot be fully understood without considering their interactions with the changes in the environment, including climate change and landscape evolution. Therefore, combining interdisciplinary information and tools will be a very powerful approach forward. Furthermore, I believe cross-system comparisons will shed great light onto fundamental biological principles and will provide the most solid base for anticipating the future of our biota. An ultimate goal of my research is to synthesize knowledge gained from different model systems, including birds, mammals, bivales, and even unconventional model systems like parasitic organisms.

Key collaborators: Dr. Paul Eizenhoefer (University of Glasgow) and Dr. Maud Meijers (University of Graz, Austria)

Figure 1 from Huang et al 2019: A hypothetical network for illustrating the complex interactions among a selection of geological (left) and biological (right) processes which might have underlain the evolution of regional biota during the time of surface uplift. The processes are illustrated as nodes, connected by arrows which indicate potential influences (double arrows for reciprocal impacts) broadly based on discussions by Hoornet al. 2010, Badgley and Finarelli 2013, Hoornet al. 2013, Mulch 2016, and Hoornet al. 2018.

Terrestrial mammals

Terrestrial mammals are an ideal system for biodiversity research because both of their rich fossil record and present-day diversity are well documented. Existing data of their spatial distribution, phylogeny, and key ecological functions of both extant and extinct lineages provide a solid foundation for investigationg how evolutionary dynamics and environmental chagnes shape their diversity patterns though time.

My current work takes advantage of their large diversity throughout Neogene and Pleistocene, which allows cross-clade, cross-region comparisons to identify underlying drivers of their body size evolution. In particular, I use a macroevolutionary framework for investigating several process that might have interacted with each other with a backgrop of climate cooling: a) the diversification process at the core of the dynamics of biodiversity (see figure below illustrating part of Huang et al 2017), b) the dynamics of geographic ranges (including change in range size and range shift through time) as one of the primary responses fo a taxon in face of environmental changes, and c) the evolution of size-related ecological traits which more directly reflect the intimate relatipnship between the animals and their environment.

Key collaborators: Dr. Juha Sarrinen (University of Helsinki, Finland), Prof. Xiangyi Li Richter (University of Bern, Switzerland), Dr. Alison Eyres (University of Cambridge), and Dr. Andrey Morozov (University of Leicester).

From Huang et al. 2017: Investigation of body size evolution in Neogene Artiodactyla in North America (upper panel) and Europe (lower panel), modified from my recent study on body size evolution in Neogene ungulates . Temporal trends of body size (a) show a significant increase in the minimum, median and maximum body sizes on both continents (p < 0.05 in all correlation test of body size change against time). Posterior distributions of the correlation parameter from a Bayesian analysis accounting for sampling and preservation bias indicate a significant correlation (i.e. the credible interval not containing 0) of body size with origination rate in both faunas (b) and with extinction rate in North America only (c upper).

Marine bivalves

Marine bivalves are distributed across all latitudes at all coastlines, and they have exceptional diversity, both taxonomically and functionally, which makes them an interesting group for biodiversity studies. They have become a model system for macroevolution research also because they have a rich and well-sampled fossil record and their contemporary diversity patterns have been well characterized.

Our team combines paleontological data of fossil bivalves and neontological data of living bivalves' distribution, functional traits, morphology and phylogeny to investigate key macroevolutionary processes leading to today's bivalve biodiversity patterns, including diversification dynamics in relation to paleoclimate, clade expansion in morphospace, and the impact of mass extinction on diversity dynamics.

Key collaborators: Dr. Stewart Edie (Smithsonian Institution, USA), Dr. Katie Collins (Natural History Museum) and Prof. David Jablonski (University of Chicago, USA)

(Photos taken at the Field Museum, Chicago)

Parasites

Parasites make a significant component of the world's biodiversity, and they can have strong influence on other components of biodiversity in many ways. They might contribute to generation of biodiversity due to their strong selection pressure on their hosts. Meanwhile, there have been numerous examples of pathogenic parasites causing severe host population declines, and many have involved pushing threatened species towards the edge of extinction. Understanding and, ultimately predicting parasite occurrence are therefore very important for wildlife management.

My parasite work investigates broad-scale infectious disease patterns from macroecological and macroevolutionary perspectives. During my PhD years, I developed a global carnivore parasite database, which is part of the larger Global Mammal Parasite Database (GMPD, http://www.mammalparasites.org/). Using parasite occurrence data from GMPD as well as host data from multiple online databases, I assessed the importance of host phylogeny, in comparison with other host ecological traits, in predicting the number of parasite species infecting a host species and the similarity of parasite species assemblages between host species.

Figure 3 from Huang et al (2014) J. Animal Ecology: Degree to which parasites are constrained by host phylogeny, expressed as the percentage of parasite species in each major group that have observed host phylogenetic species variability (PSV) equal to or below the bottom 5% quantile of the null PSV calculated from randomly selected host species. As illustrated in the conceptual graph in the upper right corner, parasites infecting hosts with a low PSV are more constrained by phylogeny than those infecting host species with a high PSV. Protozoa showed the lowest degree of phylogenetic constraint whereas viruses and helminths were most strongly restricted to related host species.

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