**3. Genetic variability as the heart of managing biodiversity**

Conservation of the genetic variability within a species is necessary as a part of global efforts to manage and conserve biodiversity. High levels of genetic variability in most natural populations of plants and animals are determinants of future population/species evolution. Genetic variability which is determined by genetic diversity can be interpreted at several levels including karyotypic variation (usually low within a species), allozyme variation (usually high within a species), and DNA sequence variation (maybe very high within a species at nongenic region e.g., short repeat sequences (microsatellites/SSR) of nuclear DNA, and maybe low within a species at genic region).

Genetic diversity can be assessed by determining kinship lineage and home range within and between a particular species/population of wildlife by using DNA analyses. Through DNA analyses, crucial information including identification of parentage, distant relatives, founders of a population, unidentified individuals, and population structure (mating system, sex ratio, estimate past population size and patterns of variability over periods time) can be correctly done to ensure genetic effective population size (Ne) is present in a particular wildlife population/species. DNA analysis expressed as genetic distance allows interpopulation comparisons to uncover spatial structuring and historical patterns of gene flow within a species. The absolute values of genetic distances which can be calculated from dissimilarities in genetic diversity vary between species, and they are increased over geological time. Therefore, accurate ESUs for effective conservation management purposes can be justified. Widely use DNA analyses by conservation geneticists are allozymes, DNA minisatellite fingerprints, RAPD, mtDNA sequences, cpDNA sequences,

genic sequences such as MHC genes, and nDNA sequences including microsatellites and SNP. The recent DNA analysis used by conservation geneticists involves the investigation of a whole-genome that is typically challenged with a huge amount of DNA base. Both nuclear and mitochondrial sequence data still provide the most informative characterizing variability at or above the level of populations. Whereas for characterizing variation within populations, polymorphic nuclear microsatellite loci and SNP are ideal markers. The various DNA analyses provide different resolutions of pedigree, population, and species-level answers and all methods are correct. Most importantly, DNA analyses can be performed for wildlife populations without requiring plants to be disturbed and animals to be seen and disturbed, as well as for museum and fossil specimens (e.g., dodo, moa, thylacine, and quagga). This can be done by using non-invasive (shed tissues, faeces, urines, and scent markings) and non-destructive (toe, tail and ear clips, and fish scales) samples. Nevertheless, DNA of some types of non-invasive and non-destructive samples may deteriorate rapidly, and hence be very difficult to work with, but it is possible with extra technical care and patience.

DNA sequence variation at the genic region is the focus of conservation geneticists. This is due to in natural populations, much of genetic variability at genic region have been discovered are appeared to be selectively neutral or near-neutral in their effects on the phenotypes (i.e., cryptic variations). Hence, the individuals carrying these allelic variants/genetic diversities appear phenotypically normal. In addition, some cryptic variations have shown circumstantial evidence that they are beneficial — provide long-term population perseverance and evolvability [5]. However, their relationship between genetic variability and individual fitness is not well understood. In a world whose change is unpredictable, alleles that are selectively neutral for thousands of generations can suddenly become a saviour for the individual who carries it. Experiments and field observations on several species have shown that there is a positive relationship between genetic variability at the genic region and individual adaptability or evolvability in important ecological aspects and significant phenotypes. The phenotypes are including body size, symmetry of body parts, growth rate, size at maturity, fecundity, hatching date, predator avoidance behaviour (e.g., escape speed, defence method, aggression, etc.), and health as measured by parasite load. Hence, conservation genetics have been putting efforts to understand genetic variability at these phenotypes through understanding the genetic diversity to explain the cause of rarity, endangerment, and extinction of a genetically deteriorate species/population. For example, cheetah (*Acinonyx jubatus*) with a low level of genetic diversity has been proved to have reduced genetic variability and hence has increased susceptibility to diseases [6, 7]. Genetic variability in these phenotypes; quantitative trait loci (QTL) are controlled by several to many genes (i.e., oligogenic and polygenic) that work additively in dominance/recessive relationships or epistatically, and their expression profiles are usually induced by environmental factors as consequences of local adaptation known as phenotypic plasticity (i.e., an adaptive mechanism). According to Fisher's fundamental theorem of natural selection, additive genetic variation (i.e., innate genetic variability; heritability (h2 )) in QTL fitness is positively related to a population's ability to respond to natural selection (i.e., evolutionary success; the ability of a species to persist despite changes in climate and environment as well as exposure to new challenges including new competitors, diseases and predators). Therefore, the heritability of such phenotypes is of conservation geneticists' interest. High heritabilities of a QTL on a trait demonstrate that a population has a great potential for evolution. Whereas low heritabilities demonstrate a more limited ability of a population to respond to environmental change. Unfortunately, such heritability is difficult to measure because it requires pedigree studies over several generations or

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

long-term manipulative experiments such as laboratory-raised plants and animals. Heritability is the ratio of the variance of a genetically inherited proportion of a trait (additive genetic variance, VA; a component in genetic variance (VG)) which response to directional selection) to the total phenotypic variance (VP) measured in a particular population and time. Estimating VA is complicated by the need to estimate environment variance (VE) as well as other genetic components in VG that are nonadditive genetic variances including dominance (VD) and epistasis (VI). However, QTL analyses using studbook records for captive populations of plants and animals, and the comparison of laboratory-raised offspring to their parents in the wild have allowed conservation geneticists to predict a reliable population's risk of extinction. This provides conservation biologists with important information on how biodiversity can be best protected against climate change and anthropogenic impacts.

On the other hand, management of genetic diversity at a large number of neutral polymorphic sites (nongenic region) has provided a useful scientific assistant to clarify for setting a species/population recovery priorities and protection. Whereby it allows more explicit estimates of Ne, migration rate, populations dynamics, and population structure (units of management). It also permits better assessment of introgression concerning management against the breeding of hybrid organisms and closely related individuals. Thus, de-extinction that is bringing back extinct wildlife species and reintroducing them to their previously inhabited landscapes with optimum Ne can be successfully done. Asexually reproducing species including clonal plants, hermaphrodite invertebrates, fish, and lizards, as well as threatened species are mostly genetically invariant in their nongenic region although they may exhibit a great ecological success [8]. Therefore, they are more prone to become extinct when their environment changes than their closely related sexually reproducing species. This has been proved in several threatened species — e.g., cheetah and ice-breeding seals whereby they are ecologically successful in the wild because of their innate genetic variability despite low absolute levels of genetic diversity; both genic and nongenic genetic diversity and being classified as threatened wildlife [8, 9].

Evolution is largely dependent on genetic variability; both genic and nongenic genetic diversity, whereby the conservation and survival of species significantly depend on the conservation of their innate genetic variability [5]. Different types of genetic variability will respond differently to evolutionary factors, population collapse, and habitat fragmentation. Hence, genetic variability is an important biological factor to determine the presence of genetic diversity or it lost, understand the causes of the loss and make recommendations to overcome its ultimate effects in wildlife conservation.
