Species-specific genetic variation in response to deep-sea environmental variation amongst Vulnerable Marine Ecosystem indicator taxa

Cong Zeng,Malcolm R Clark,Ashley A Rowden,Jonathan P A Gardner

doi:10.1038/s41598-020-59210-0

Abstract

Understanding the ecological processes that shape spatial genetic patterns of population structure is critical for understanding evolutionary dynamics and defining significant evolutionary and management units in the deep sea. Here, the role of environmental factors (topographic, physico-chemical and biological) in shaping the population genetic structure of four deep-sea habitat-forming species (one sponge - Poecillastra laminaris, three corals - Goniocorella dumosa, Madrepora oculata, Solenosmilia variabilis) was investigated using seascape genetics. Genetic data (nuclear and mitochondrial sequences and microsatellite multilocus genotypes) and environmental variables were employed to build individual-based and population-level models. The results indicated that environmental factors affected genetic variation differently amongst the species, as well as at different geographic scales. For individual-based analyses, different environmental variables explained genetic variation in P. laminaris (dissolved oxygen), G. dumosa (dynamic topography), M. oculata (sea surface temperature and surface water primary productivity), and S. variabilis (tidal current speed). At the population level, factors related to current and food source explained the regional genetic structure in all four species, whilst at the geomorphic features level, factors related to food source and topography were most important. Environmental variation in these parameters may be acting as barriers to gene flow at different scales. This study highlights the utility of seascape genetic studies to better understand the processes shaping the genetic structure of organisms, and to identify environmental factors that can be used to locate sites for the protection of deep-sea Vulnerable Marine Ecosystems.

Highlights

How spatially variable environmental and habitat features influence evolutionary processes and population genetic connectivity in the deep sea is poorly understood[1,2,3]
Whilst seascape genetics holds much promise for delivering a new understanding of how environmental variation influences genetic variation it is important to appreciate that seascape genetics is in its infancy and we are still learning about its limitations and possibilities
The results provide information about which environmental variables contribute most to the genetic structure of populations of the four species, how connectivity amongst vulnerable marine ecosystems (VMEs) is influenced by environmental variation, if environmental variation plays a consistent role across multiple taxa in explaining population genetic structure, and how such information may be used to inform appropriate management measures, which in the present context, are likely to involve the establishment of a new offshore network of marine protected areas

Summary

Introduction

How spatially variable environmental and habitat features influence evolutionary processes and population genetic connectivity in the deep sea is poorly understood[1,2,3]. Because of its highly variable seafloor topography and bathymetry and its complex patterns of oceanic dynamics, New Zealand presents an ideal opportunity to test the effect of multi-factorial environmental influences on the genetic variation of deep-sea species Such testing may be carried out at different spatial scales that are relevant to species’ distributions across the New Zealand region. Significant genetic differentiation was detected at the bioprovince, regional and geomorphic features scales in both P. laminaris and S. variabilis, at the regional and geomorphic features scales in G. dumosa, but only at the regional scale in M. oculata[3,14] These different patterns of genetic structure may be related, at least in part, to species-specific reproductive strategies[1,6], but a major limitation of research of this kind is that we know very little about the mode of reproduction or the larval dispersal ranges of most deep-sea species[1]. There is an indication that larval dispersal potential may be positively correlated with oocyte size amongst Goniocorella dumosa, Madrepora oculata and Solenosmilia variabilis[3]

Methods

Results

Conclusion