Final answer:
To determine genetic or environmental sex determination, examine the presence of sex chromosomes and their role in determining sex. Evidence of specific genes or markers on sex chromosomes and the sex chromosome to autosome ratio can help determine the cause of sex determination in genetic systems.
Step-by-step explanation:
To determine if a species has genetic sex determination, you would look for the presence of sex chromosomes and observe how they determine the sex of individuals. For example, in mammals, the presence of a Y chromosome leads to male development and its absence results in female development. In species with environmental sex determination, you would look for the influence of environmental factors, such as temperature, on the sex of individuals. For instance, in some reptiles, warmer temperatures during egg incubation result in female offspring, while cooler temperatures produce males.
In terms of determining what causes sex determination in species with genetic sex determination, evidence such as the presence of specific genes or genetic markers on sex chromosomes can be examined. For example, the SRY gene on the Y chromosome is responsible for male development in mammals. Another important piece of evidence is the sex chromosome to autosome ratio. In species where sex determination is influenced by the presence of particular sex chromosomes, a specific ratio may indicate the likelihood of male or female development.