The impact of genetic parental distance on developmental stability and fitness in Drosophila buzzatii

Abstract

Measures of genetic parental distances (GPD) based on microsatellite loci (D(2) and IR), have been suggested to be better correlated with fitness than individual heterozygosity (H), as they contain information about past events of inbreeding or admixture. We investigated if GPD increased with increasing genetic divergence between parental populations in Drosophila buzzatii and if the measures indicate past events of admixture. Further we evaluated the relationship between GPD, fitness and fluctuating asymmetry (FA) of size and shape. We investigated three populations of Drosophila buzzati, from Argentina, Europe and Australia. From these populations two intraspecific hybridisation lines were made; one between the Argentinean and European populations, which have been separated 200 years and one between the populations from Argentina and Australia, which have been separated 80 years. By doing this we obtained hybrid progeny having different levels of GPD. We found that D(2) and H can be used as indicators of admixture when comparing hybrid individuals with their parentals. IR was not informative. Our results does not exclude the presence of genetic fitness correlations (GFC) over individuals with a broad fitness range from populations in equilibrium, but we doubt the presence of GFC using GPD measures in admixed populations. Shape FA could be a relevant measure for fitness, however, only when comparing populations, not at individual level.

Outbreeding causes developmental instability in Drosophila subobscura

“…For example, if recessive deleterious alleles are present in the parental populations in high frequency, hybridization will mask such recessive variation and heterosis is expected. In contrast, under some scenarios of overdominant selection, outbreeding depression might be expected, particularly if different pairs of alleles are most fit in different populations or if only one of the populations is subject to overdominant selection at the locus (Charlesworth and Hughes 1999;Garnier et al 2006;Andersen et al 2008).…”

“…In the other words, they become coadapted and increase the fitness of populations which suggest that the specific association of coadaptive gene complexes are the most probable mechanism that maintains the developmental homeostasis in populations. In the case of hybridisation between two different populations (interpopulation crosses), coadaptive gene complexes were disrupted because the new recombination due to divergence in selection for local adaptation between the two populations So, the new gene complexes will be expected to decrease overall fitness and individuals and populations will experience outbreeding depression (Dobzhansky 1936;Orr 1995;Burke et al 1998;Andersen et al 2002Andersen et al , 2008Edmands 2007). The impact of outbreeding depression on populations differs and depends on the amount of genes involved in the coadapted gene complexes.…”

“…Although no clear patterns have been found, several trends emerged. Available data indicate a tendency of FA to increase with inbreeding and population hybridization (Palmer and Strobeck 1986;Waldmann 1999;Lens et al 2000;Garnier et al 2006;Andersen et al 2008). There is evidence which suggests a positive correlation between FA and genomic stress (Leary and Allendorf 1989).…”

A Study of Canalization and Developmental Stability in the Sternopleural Bristle System of Drosophila Melanogaster

“…Andersen et al 2002Andersen et al , 2006Garnier et al 2006). One commonly used measure of DI is fluctuating asymmetry (FA), or the difference in value between paired bilateral traits, which is known to be elevated due to environmental stresses and genetic factors such as hybridization (Andersen et al 2002(Andersen et al , 2006(Andersen et al , 2008Kristensen et al 2003Kristensen et al , 2004Røgilds et al 2005;Pertoldi et al 2006a;Petavy et al 2006;Lens et al 2000;Soderman et al 2007;Krag et al 2009). The reason for the increased FA in intraspecific hybrids has been attributed to a breakdown in co-adapted gene complexes (Andersen et al 2002), whereas in interspecific hybrids increased FA has more often been attributed to genetic incompatibilities causing meiotic irregularities or physiological and developmental abnormalities (Andersen et al 2006;Burke and Arnold 2001;Pialek et al 2001;Rego et al 2006;Kurbalija et al 2010).…”

Increased Fluctuating Asymmetry in a Naturally Occurring Hybrid Zone between the Stick InsectsBacillus Rossius RossiusandBacillus Rossius Redtenbacheri

“…Andersen et al 2002, 2006; Garnier et al 2006). One commonly used measure of DI is fluctuating asymmetry (FA), or the difference in value between paired bilateral traits, which is known to be elevated due to environmental stresses and genetic factors such as hybridization (Andersen et al 2002, 2006, 2008; Kristensen et al 2003, 2004; Røgilds et al 2005; Pertoldi et al 2006a; Petavy et al 2006; Lens et al 2000; Soderman et al 2007; Krag et al 2009). The reason for the increased FA in intraspecific hybrids has been attributed to a breakdown in co-adapted gene complexes (Andersen et al 2002), whereas in interspecific hybrids increased FA has more often been attributed to genetic incompatibilities causing meiotic irregularities or physiological and developmental abnormalities (Andersen et al 2006; Burke and Arnold 2001; Pialek et al 2001; Rego et al 2006; Kurbalija et al 2010).…”