Final answer:
Polyandrous mating systems are less common than polygynous ones due to the energetics of mating strategies and parental care, where in polygynous systems, a single male mates with multiple females who provide most or all offspring care. This system is advantageous where females select males based on resource-rich territories, ensuring a higher offspring survival rate. Polyandry, where one female mates with multiple males, is less advantageous in terms of resource allocation and reproductive success.
Step-by-step explanation:
Polyandrous mating systems, where one female mates with multiple males, are much rarer than polygynous matings because of the difference in parental care and mating strategies. In polygynous systems, one male mates with multiple females, often leading to females being solely responsible for parental care. As a result, females are drawn to males with territories rich in resources, a trait indicating high genetic quality and ensuring a better survival rate for the offspring, despite the absence of male parental support.
Such resourced-based polygyny allows dominant males to mate with many females, for example, with the yellow-rumped honeyguide defending beehives. Other variations include harem mating structures, where alpha males dominate the mating within a group, which is seen in elephant seals. Furthermore, there are lek systems, communal courting areas where females choose their mates from performing males, a behavior observed in sage grouse and prairie chickens.
In contrast, polyandry may be less common because it typically requires the females to establish territories to attract multiple males, which is energetically costly and may not provide the same reproductive advantage as the prolific resource-based polygyny.