Are sandbar sharks more like bowhead whales or cod?
At first glance, the question posed in the title seems silly. Both cod and sandbar sharks are fish, therefore they must be more similar to each other than either are to bowhead whales (which are mammals). However, a recent conservation genetics paper has demonstrated that one aspect of a sandbar shark’s life history is more similar to that of bowhead whales: both sandbar sharks and bowhead whales have an effective size that is very similar to their census size. For an explanation of effective size (Ne), please see Andrew’s Crowdsourcing ConGen post. Fisheries managers have become more interested in measuring Ne because of a growing concern that fishing is altering the genetic diversity of certain stocks. Census size (Nc) is a much simpler concept- it is simply the number of individuals in a population. A subset of this is the number of effective breeders. Note that this is smaller than the total population, since not every individual in the population is of breeding age. However, from
