BIO.10.B

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The student is expected to analyze and evaluate how the elements of natural selection, including inherited variation, the potential of a population to produce more offspring than can survive, and a finite supply of environmental resources, result in differential reproductive success;
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Knowledge and Skills Statement

Science concepts--biological evolution. The student knows evolutionary theory is a scientific explanation for the unity and diversity of life that has multiple mechanisms.

the theory in biology postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations

a natural process that results in the survival and reproductive success of individuals or groups best adjusted to their environment and that leads to the perpetuation of genetic qualities best suited to that particular environment

the differences in characteristics between organisms of the same population

Research

Yeo, Alexander R., and James F. Hare. "Richardson's ground squirrel litter size-sex ratio trade-off reveals conditional adaptive sex allocation." Oecologia 195, no. 4 (April 2021): 915-925. doi: 10.1007/s00442-021-04900-3.

Summary:  Trivers and Willard proposed that female mammals should adjust their investment in male versus female offspring relative to their ability to produce high-quality offspring. We tested whether litter size-sex ratio trade-offs predicted by Adaptive Sex Allocation (ASA) theory occur among Richardson's ground squirrel (Urocitellus richardsonii) dams over 10 distinct breeding years in a population where individuals experienced variability in food availability and habitat disruption.

Research

Cafazzo, Simona, Roberto Bonanni, Paola Valsecchi, and Eugenia Natoli "Social Variables Affecting Mate Preferences, Copulation and Reproductive Outcome in a Pack of Free-Ranging Dogs." PLoS ONE 9, no. 6 (June 2014): e98594. https://doi.org/10.1371/journal.pone.0098594

Summary:  Mating and reproductive outcome is often determined by the simultaneous operation of different mechanisms like intra-sexual competition, mating preferences, and sexual coercion. The present study investigated how social variables affected mating outcomes in a pack of free-ranging dogs, a species supposed to have lost most features of the social system of wolves during domestication. To our knowledge, these results provide the first clear evidence of social regulation of reproductive activities in domestic dogs, and suggest that some common organizing mechanisms may contribute to shape the social organization of both dogs and wolves.