Conservation Genetics for Managing Biodiversity

*Nurul Izza Ab Ghani, Wardah Arifin and Ahmad Ismail*

## **Abstract**

Conservation genetics is a field derived from a combination of evolution, ecology, behaviour, and genetics. It is an applied discipline of crisis-oriented science of biodiversity resource management that is highlighted when the world realizes the increasing anthropogenic impact and natural populations are declining towards species extinction. It helps to understand and explain the importance of evolutionary factors — mutations, non-random mating, gene flow, genetic drift, and natural selection — for the survival of populations/species that justify the need for prudent biodiversity management. The four justifications for maintaining prudent biodiversity are the economic value of bioresources, ecosystem services, esthetics, and rights of living organisms to exist ensure functioning community and ecosystem services. Hence, conservation genetics must be an essential part of policies and programs in wildlife and biodiversity management.

**Keywords:** biodiversity, conservation, evolutionary factors, genetic management, genetic variability

## **1. Introduction**

The need to preserve wildlife arises because the earth's biological diversity is rapidly depleted as a direct or indirect result of human action. To date, a number of unknown but many species have become extinct, meanwhile many other species have reduced population sizes and putting them at risk of extinction. IUCN [1] reported that more than 38,500 species are threatened with extinction — highlighting 26% of mammals, 14% of birds, 41% of amphibians, 37% of sharks and rays, 28% of selected crustaceans, 34% of conifers, and 33% of reef corals. Hence, many species are now required human intervention to ensure their survival through effective management and conservation of biodiversity resources. But a statistically robust Population Viability Analysis (PVA) has yet to be developed to assess the ecological and genetic risks faced by the Essential Evolutionary Unit (ESU) which is the unit of biodiversity that is of concern to conservation geneticists. Though, International Union for Conservation of Nature (IUCN) has recognized the need to manage and conserve biodiversity resources at three levels; genetic diversity, species diversity, and ecosystem diversity. Genetic information is involved in all of these three levels. Thus, geneticists (specifically known as conservation geneticists) are playing an increasingly important role in the management and conservation of biodiversity resources — identifying and monitoring the genetic variability that directly relates to evolutionary factors of biodiversity units.

Conservation geneticists deal with evolutionary factors causing rarity; endangerment and extinction of threatened population and species, and genetic management to minimize impacts of evolutionary factors in threatened population and species, as well as resolving taxonomic uncertainties in threatened species, understanding the biology of threatened population and species through their genomic, and wildlife forensics. All of these are important research courses in conservation genetics with the ultimate goal to manage biodiversity resources with utmost care through preserving and maintaining the ability of populations and species to evolve. Thus, reducing the extinction risk of population and species, while ensuring a functioning community and ecosystem services. All research courses in conservation genetics can be disentangled by using molecular genetics methods through the use of various molecular markers. The common molecular markers which have been used are single-locus markers (allozymes), DNA minisatellite fingerprints, random amplified polymorphic DNA (RAPD), mitochondrial DNA (mtDNA) sequences, chloroplast DNA (cpDNA) sequences, genic sequences such as Major histocompatibility complex (MHC) genes, and nuclear DNA (nDNA) sequences including microsatellites and single nucleotide polymorphism (SNP). To date, conservation geneticists also have started to use whole-genome sequence which offers a more powerful assessment to disentangle evolutionary factors and their implications towards population/species rarity and survival to manage biodiversity.

Yet, efforts to implement conservation genetics for managing biodiversity have been done for very few threatened species. Therefore, the aim of this chapter is to briefly highlight the importance of assimilating conservation genetics to manage biodiversity with a review of the relevant literature. This chapter is comprised of three parts. The first part introduces readers to the genetic management of biodiversity units that are seldom been misinterpreted. The second part points out the essence of genetic variability in managing biodiversity due to its importance for determining future population/species evolution. The final section hopes to engage readers with an appreciation of research courses in conservation genetics by briefly describing evolutionary factors influencing genetic variability of threatened populations/species including mutations, non-random mating, gene flow, genetic drift, and natural selection.

## **2. Genetic management of biodiversity unit**

Poorly planned conservation management plans can significantly cause local adaptation damage (overcoming depression) and reduce the viability of the population, especially the threatened population. PVA is a methodology that has been used by conservation geneticists to assess the ecological and genetic risks faced by wildlife or captive population, and thus appropriate conservation management plan can be developed. PVA refers to a group of mathematical models that are useful for predicting the probability of population extinction at some point in the future. The early PVA models considered demographic data (growth rate, current population size, and birth rate) and environmental stochastic data. But Gilpin and Soulé [2] has been further enhanced the ability of the PVA model in predicting the extinction of a species by including genetic factors. Genetic factors including mutation, genetic drift, non-random mating, gene flow, and natural selection have significantly influenced genetic variability. It is clearly expressed through its effects on demographic factors that influence population dynamics, especially in small isolated/threatened populations. This shows that genetic factors contribute to extinction probabilities through a very complex manner of interactions affecting the genetic variability and fitness of a population [3, 4]. Unfortunately, little is understood regarding genetic

#### *Conservation Genetics for Managing Biodiversity DOI: http://dx.doi.org/10.5772/intechopen.101872*

factors' linkage to ecological factors. Thus, statistically strong PVAs have not yet been developed sufficiently to provide comprehensive biodiversity management.

The biodiversity unit of concern by conservation geneticists in PVA is ESUs. ESUs represent genetically differentiated populations whereby depicting deep phylogenetic subdivisions typically within a species (i.e., subspecies) or occasionally as entire species in the case of local endemics or distinct population segments (DPS - Endangered Species Act 1973). ESUs are classified based on genetic criteria; both genetic diversity and multilocus genetic similarity using multilocus mtDNA or nDNA (preferably microsatellites) variation. mtDNA shows evidence for significant long-term genetic divergence and reciprocal monophyly. Whereas microsatellites show evidence for the significant recent divergence of allele frequencies at nuclear loci. A refine ESUs in wildlife conservation include pedigree analysis. Pedigree analysis has been used to understand the established kinship and individual founder contributions, to determine genetically desirable and undesirable individuals as well as their descendants, to elucidate population structure and mating system, and to designate appropriate individuals for translocation or reintroduction. Hence, pedigree management programs based on mean kinship or minimal founder contributions are commonly used to minimize inbreeding in local subpopulations and metapopulations. Delineating refine ESUs is important when considering longterm conservation actions especially translocations and captive breeding programs. Translocation between ESUs should be avoided in order to successfully replenish the diversity and viability of severely declining and nearly monomorphic populations with severe inbreeding depression (low heterozygosity, low fertility (e.g., poor sperm and ovum quality and cryptorchidism), and low disease susceptibility). Whereas captive breeding programs between ESUs may lead to reduce genetic variability and increase populations' susceptibility to extinction.
