Final answer:
Scientists can determine a species' population size by studying genetic diversity, which involves collecting DNA samples and analyzing genetic markers to evaluate genetic health and adaptability.
Step-by-step explanation:
To determine the population size of a species, scientists collect various types of data. One critical aspect is assessing the genetic diversity within the species. Genetic diversity is essential because it reflects the health of a population and its ability to adapt to environmental changes. To measure this, researchers might analyze genetic markers in DNA samples from individuals across the population, looking for the presence of different alleles and genetic variants.
Methods such as gene sequencing and genotyping are commonly used to assess genetic diversity. Studies might involve fieldwork to collect specimens like blood, tissue, or even seeds in the case of plants. Through genetic analysis, scientists can evaluate levels of inbreeding, determine the genetic basis of traits, and understand gene frequency changes over time — factors that all contribute to understanding a species' resilience and conservation needs.