Number of Immunoreactive GnRH‐Containing Neurons Is Heritable in a Wild‐Derived Population of White‐Footed Mice (Peromyscus leucopus)

Abstract

The evolution of mammalian brain function depends in part on levels of natural, heritable variation in numbers, location, and function of neurons. However, the nature and amount of natural genetic variation in neural traits and their physiological link to variation in function or evolutionary change are unknown. We estimated the level of within-population heritable variation in the number of gonadotropin-releasing hormone (GnRH) neurons, which play a major role in reproductive regulation, in an unselected outbred population recently derived (<10 generations) from a single natural population of white-footed mice (Peromyscus leucopus, Rafinesque). Young adult male mice exhibited an approximately threefold variation in the number of neurons immunoreactive for GnRH in the brain areas surveyed, as detected using SMI-41 antibody with a single-label avidin-biotin complex method. Consistent with earlier findings of selectable variation in GnRH neurons in this population, the level of genetic variation in this neuronal trait within this single population was high, with broadsense heritability using full-sib analysis estimated at 0.72 (P<0.05). Either weak selection on this trait or environmental variation that results in inconsistent selection on this trait might allow a high level of variation in this population.

Effects of photoperiod and food restriction on the reproductive physiology of female California mice

“…After washing in PBS, stained sections were mounted onto Superfrost plus slides (Fisher) and coverslipped using Vectashield Mounting Medium (Vector Laboratories). Both the GnRH [15] and GFAP [40] primary antibodies have been previously validated in Peromyscus. …”

Variation in levels of luteinizing hormone and reproductive photoresponsiveness in a population of white-footed mice (Peromyscus leucopus)

“…Natural populations of temperate-zone rodents contain substantial functional and genetic interindividual variation in this trait (5,8,10,17,19,33). Interindividual variation in the GnRH neuronal system has been correlated with variation in reproductive suppression (1,18,29), suggesting that variation in the GnRH neuronal system is related to interindividual variation in reproductive suppression in winter. Because GnRH neurons control LH secretion, interindividual variation in level of LH is a functional mechanism by which genetic variation in the HPG axis could directly affect reproductive phenotype.…”

Nature or Nurture? Heritability in the Classroom

“…Within a decade, research aimed at estimating heritabilities of physiological and related traits had become a mainstream component of the new evolutionary physiology (Garland and Carter 1994; see also Feder et al 2000). At present, estimating heritability (Hawks 2011; Brookfield 2012) is fairly common in the ecological and evolutionarily subfields of physiology (e.g., Dohm et al 2001;Nespolo et al 2003;Heideman et al 2007;Sadowska et al 2009;Careau et al 2011;Bruning et al 2013;Fuchikawa and Okada 2013;Mattila and Hanski 2014;review in Storz et al 2015), as well as fields that are increasingly incorporating information from the physiological sciences, such as behavioral ecology (e.g., Dochtermann et al 2014;Petelle et al 2015). Heritability also remains a key topic in animal breeding (e.g., Velie et al 2015), in the biomedical sciences (e.g., Wood et al 2008;Fernández-Grandon et al 2015;Ganjgahi et al 2015), and indeed in the biological sciences generally (Visscher et al 2008).…”