In today’s world with an increasing human footprint across the natural world, scientists believe we may be entering a sixth mass extinction. Fragmented habitats, introduction of invasive species, and climate change are just some of the factors leading to this mass extinction. A lot of species still have yet to be recorded, so the number of extinctions of populations and species documented by scientists are likely to be large underestimates (Barnosky et al. 2011). Climate change is one factor among many that is leading to the loss of biodiversity. Therefore, it is important for scientists to understand how populations respond to rapid environmental change. It is known that evolutionary history may affect risk of extinction within populations due to the accumulation of mutations, or pleiotropy. In one environment certain mutations will be favored, but in others they may have detrimental effects that reduce fitness, or reproductive success of a certain genotype in a population. (genotype being the genetic makeup of an individual) This would lower a population’s ability to withstand environmental change due to the accumulation of mutations which aren’t suited for the new environment. (MacLean et al. 2004) Understanding evolutionary history is crucial for understanding how populations will respond to environmental change caused by climate change. In the October edition of the Journal of Evolutionary Biology there was a study looking at how evolutionary history affects extinction probability. Its title is “The effect of selection history on extinction risk during severe environmental change”. This study looked at how the extinction risk of populations of the green algae Chlamydomonas reinhardtii changed with various stressful environments (Lachapelle et al. 2017).
A parasite is an organism that lives in or on another organism at that organism’s expense. For most people, the thought of a parasite is usually in the form of leeches, tapeworms, or ticks. Within populations, parasites have the power to dictate the health of a population and which individuals survive. From an evolutionary standpoint, this can determine who in a population survives due to a parasites ability to kill off the defenseless, and therefore allow individuals with only specific traits to survive. Under the basic concept of natural selection: those who survive, pass on their traits, while the unfit individuals die and fail to pass their traits to the next generation. Parasites act as a controlling factor for which hosts and genes survive for reproduction. With this in mind, Charles R. Brown and Mary Bomberger Brown began a study to investigate the effect of parasitic cimicid bugs on the brood size of cliff swallows (Brown and Brown 2017).
In 1998, one of Charles Darwin’s famous finches, the medium tree finch, was classified as threatened on the International Union for Conservation of Nature’s (ICUN) red list (BirdLife, 2018). The medium tree finch, otherwise known as Camahynchus pauper, was named for the size of its short, curved beak. It can be found living only on Floreana island, an island that is part of the Galapágos Islands archipelago (bottom center of fig. 1). Over the last couple hundred years, this finch has faced numerous threats to its survival in the form of habitat fragmentation and destruction, predation, and now specifically parasitism (Kleindorfer et al., 2014). In 2009, the species was bumped all the way up to being labelled as critically endangered, after its population numbers dipped, largely due to threats caused by humans (BirdLife, 2018).
Coral reefs are prime examples of thriving diversity, none more than the Coral Triangle, which is located in the ocean surrounding the archipelagos of the Philippines and other islands above Australia, pictured in the orange area of Figure 1. For hundreds of years, the Coral Triangle has fascinated scientists. This area contains more species of corals than any other area in the world, but scientists do not know how so many corals came to occupy the Coral Triangle. Recently, a group of scientists led by Danwei Huang came together to investigate four hypotheses on diversity in hopes to find which one is most accurate with regard to the corals of the region.