The first global macrogenetic map of the species that make up marine habitats has been published

2023-05-29 13:45:21

The species known to form marine habitats (gorgonians, corals, algae, marine phanerogams, etc.) are organisms that help generate and structure underwater landscapes. They are a natural refuge for other species, contributing biomass and complexity to the seabed. But these key species in marine ecosystems are currently under threat from global climate change and other disturbances from human activity.

Now, a study, in which the first global macrogenetic map of the species that make up marine habitats has been drawn up, warns that even in marine protected areas the genetic diversity of structural species is not protected, although this is essential for the adaptation of populations to changes that alter the natural environment.

The study is the work of Laura Figuerola-Ferrando, Cristina Linares, Ignasi Montero-Serra and Marta Pagès-Escolà, from the Faculty of Biology of the University of Barcelona (UB) and the Biodiversity Research Institute of the UB (IRBio) ; Jean-Baptiste Ledoux and Aldo Barreiro, from the Centro Interdisciplinary de Investigación Marine y Ambiental (CIIMAR) in Portugal, and Joaquim Garrabou, from the Instituto de Ciencias del Mar (ICM) attached to the Consejo Superior de Investigaciones Científicas (CSIC) in Spain.

Genetic diversity is also a component of biodiversity

Traditionally, management and conservation plans for marine biodiversity have considered factors such as species richness. Genetic diversity —another main component of biodiversity— reflects the genetic variety that exists between organisms of the same species and is a determining factor in the adaptive capacity of populations and their survival. Despite its importance, genetic diversity has so far been ignored in management and conservation plans.

“Genetic diversity plays a key role in promoting a greater capacity of species, populations and communities to adapt to the rapid environmental changes derived from climate change and thus increase their resilience”, details the researcher Laura Figuerola-Ferrando.

“However, until now the vast majority of marine protected areas are implemented based on the presence of various species and habitats, without taking into account their genetic diversity. Another example would be the red list of the International Union for Conservation of Nature (IUCN), which also does not contemplate genetic diversity », he adds.

In recent years, the need to broaden conservation efforts to protect genetic diversity is being reinforced. “Technological progress in the massive development of different techniques to determine genetic diversity (for example, through the use of microsatellites or small fragments of DNA), as well as their affordable cost, can help to include genetic diversity in management plans and conservation”, details the researcher from the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB.

The research highlights the relevance of including genetic diversity in marine life conservation and management plans. (Photo: MedRecover Research Group. CC BY)

From the Northwest Atlantic to the Gulf of Guinea

The new study applies macrogenetic techniques to identify general genetic patterns in various marine species at large spatial scales. The authors have analyzed data from a global database containing information on the genetic diversity (based on microsatellites) of more than 9,300 populations of 140 species in different marine regions across the planet.

The results outline a reference scenario of genetic patterns in species that form marine habitats (corals, macroalgae, marine phanerogams, etc.) of potential interest in improving management and conservation plans for marine life.

The Northwest Atlantic and the Bay of Bengal are the regions where the greatest genetic diversity has been identified in marine habitat-forming species. Quite high values ​​(above the global average) have also been identified in the Mediterranean. Conversely, the marine areas with the lowest values ​​of genetic diversity are the Gulf of Guinea and the southwestern Atlantic.

The findings also indicate a positive correlation between genetic diversity and species richness of both animal and plant marine habitat-forming species. However, the work alerts to a worrying result: the Network of Marine Protected Areas (RAMP) in the large oceanic ecoregions does not preserve areas in which the genetic diversity of marine habitat-forming species is greater.

“What we have seen is that what is not being protected in marine protected areas is genetic diversity. In the study, the initial hypothesis suggested that there would be greater genetic diversity within these areas, but this has not been the case. In fact, at a global level we have seen that there are no differences in genetic diversity between inside and outside marine protected areas”, explains Laura Figuerola-Ferrando, who is doing her doctoral thesis under the direction of Cristina Linares (UB) and Joaquim Garrabou (ICM).

A new pattern of biodiversity

The authors of the study have also identified a specific pattern in the distribution of genetic diversity of marine habitat-forming species that differs from traditional models known up to now. “This is a bimodal latitudinal pattern: it is a complex biogeographic model and it implies that if we model how the genetic diversity of these species varies with latitude, we find two peaks in temperate zones and a small dip in genetic diversity at the equator,” details Professor Cristina Linares (UB-IRBio), one of the coordinators of the study together with Jean-Baptiste Ledoux (CIIMAR).

This scientific discovery is relevant because until a few decades ago it was considered that the distribution of biodiversity on the planet followed a unimodal pattern, that is, it had maximum values ​​at the equator and decreased towards the poles. “This is not always the case, especially in terms of species diversity in marine ecosystems. For example, in the case of benthic species, this pattern is more bimodal than unimodal both in terms of species richness and genetic diversity,” explains Cristina Linares.

“In our study, the bimodal latitudinal pattern is influenced by taxonomy: in the model used, we found statistically significant differences between animal (more genetic diversity) and plant (less genetic diversity) species. In addition, if we explore the latitudinal pattern separating the species of animals and plants, we can see how a bimodal pattern continues to be observed in animals, while the same cannot be said of plants”, adds the researcher Jean -Baptiste Ledoux ( CIIMAR).

The conclusions of the work recall the need to include the genetic diversity of populations in the management and conservation plans for biodiversity on the planet.

This work also reveals that the Mediterranean and Atlantic regions are among the most present in the scientific bibliography used in this work on the macrogenetic patterns of the structural species of the seabed.

The study is titled “Global patterns and drivers of genetic diversity among marine habitat-forming species”. And it has been published in the academic journal Global Ecology and Biogeography. (Source: UB)