Lineage Loss in Serengeti Cheetahs: Consequences of High Reproductive Variance and Heritability of Fitness on Effective Population Size

Abstract

In natural populations, many breeders do not leave surviving offspring, and as a result many potential genetic lineages are lost. I examined lineage extinction in Serengeti cheetahs ( Acinonyx jubatus ) and found that 76% of matrilines were lost over a 25-year period. Production of future breeders was nonrandom and generally confined to a few families. Five out of 63 matrilines accounted for 45% of the total cheetah population over the course of the study. Lineage persistence is perhaps best illustrated by the variance in lifetime reproductive success (LRS) and heritability in this parameter. In female cheetahs, variance in LRS was high, and new data show that this LRS was heritable. Variance in LRS and heritability in LRS have dramatic consequences for effective population size, N e . I calculated N e for cheetahs, taking into account fluctuating population size, unequal sex ratio, non-Poisson distribution of reproductive success, and heritability of fitness. The N e was most strongly affected by variance in reproductive success and especially heritability in reproductive success. The variance N e was 44% of the actual population size, and the inclusion of heritability further reduced N e to only 15% of the actual population, a ratio similar to that of a social carnivore with reproductive suppression. The current cheetah population in the Serengeti is below numbers suggested by N e estimates as sufficient to maintain sufficient genetic diversity.Pérdida de Linaje en Cheetas del Serengueti: Consecuencias de una Varianza Reproductiva Alta y de la Herencia de la Adaptabilidad en el Tamaño Poblacional

Effective size of populations with unequal sex ratio and variation in mating success

“…The correlation could be positive if parents and offspring both occupy an especially favourable niche. For example, from mother‐daughter regression, Kelly (2001)estimated the heritability of female family size in Serengeti cheetahs as 0.89. This high heritability estimate strongly suggests the presence of an environmental correlation.…”

“…Thus, as a first approximation, the effective size ( N e ) has been estimated by accounting only for unequal sex ratio (e.g. Lacava and Hughes 1984; Chepko‐Sade et al 1987; Kelly 2001), using a well‐known formula ( Wright 1931) where N m and N f are the numbers of breeding male and female parents, respectively.…”

Fitness-related patterns of genetic variation in rhesus macaques

“…Studies of human populations and wild mammals have calculated large heritability of fitness (e.g. Pettay et al 2005;Reale and Festa-Bianchet 2000;Kelley 2001). Second, there are a number of processes that could result in modest-high heritability of fitness.…”

The role of vocal individuality in conservation

“…Other bird species have yielded similar values [26]. Kelly [27] showed that a few (8%) cheetah ( Acynonyx jubatus ) matrilineages produced over 50% of the population over a 20-year period, and studies in other mammals have yielded equally high differences in reproductive success [28,29]. …”