Testing the Role of Predation in Morphological Evolution of Marine Prey

捕食，一种生物杀死另一种生物以获取食物的行为，被认为会极大地影响物种的进化和多样性（数量）。我们目前正在经历一场生物多样性危机（每天有70个物种灭绝），因此了解影响多样性和进化的因素至关重要。有一种“升级”假说认为，大多数动物进化的主要原因是为了更好地保护自己免受捕食者的攻击。化石记录为检验这些假设提供了一个长期的自然实验室。然而，捕食很难估计，因为对过去的直接观察是不可能的。因此，我们需要一种不用直接观察就能估计捕食的方法。一种解决办法是利用捕食的痕迹，比如海洋无脊椎动物被捕食的贝壳上的伤疤，来估计捕食的频率。例如，螃蟹经常以蛤蜊为食，用它们有力的爪子折断蛤壳。如果攻击失败，蛤会重新长出外壳，外壳上现在有一个修复疤痕；我们可以在化石上看到这样的伤痕。

Predation, the act of an organism killing another for food, is believed to influence the evolution and diversity (the number) of species greatly. We currently are experiencing a biodiversity crisis (70 species go extinct per day) so understanding the factors that influence diversity and evolution is vital. There is a hypothesis of “escalation”, which suggests that the main reason why most animals evolve is to defend themselves better from their predators. The fossil record provides a long-term natural laboratory to examine such hypotheses. However, predation is hard to estimate because direct observations of the past are impossible. Thus, we need a means of estimating predation without direct observations. One solution is to use traces of predation, such as scars on the shells of marine invertebrate prey, to estimate the frequency of predation. For example, crabs regularly feed on clams by using their powerful claws to fracture the shell. If the attack fails, then the clam regrows its shell, which now has a repair scar; we can see such scars on fossils.