Two of the most important factors when considering rapid evolution are the generation time and environmental conditions throughout the life history of a species. For a species to evolve rapidly, it must have certain selection pressures, such as the aforementioned mass extinction which can lead to rapid evolution, or short generation times which would result in higher mutation, and therefore higher adaptation rates. Adaptation relies on random genetic mutations, and as a more favourable mutation survives, it is more likely to be passed on to the next generation. Long-lived species are therefore more restricted, being unable to change or adapt at the same rate as the faster evolving short-lived species (WEB jrank). An example of a fast evolving species is that of the Southeast Asian tree shrew (Tupaia belangeri).
Directional selection and disruptive selection are two of the three types of natural selection. Although both of them result in a population adapting to biotic and abiotic environments, they differ in many ways. Directional selection occurs when one extreme phenotype is favored over the other phenotypes, whereas disruptive selection occurs when two or more phenotypes are favored over the others. Another difference is that disruptive selection favors polymorphism and directional selection causes species to evolve over time and leads to the extinction of those lacking the phenotypes causing the distribution curve to shift.
Throughout the history of the world, species have evolved to adapt to their changing environment. Some species have excelled at this and have adapted well; others have struggled to survive and are facing the danger of extinction. Mankind must decide if keeping these failing species alive is worth the cost and resources. Each species is unique and different, and their contributions vary. Each should be considered on an individual basis.
Animals and plants become at risk for extinction, or endangerment, when environments and ecosystems are changed by human activities or other natural causes (Wright & Boorse, 2014). Regrettably, human activity is usually the source of environmental change and endangerment to a species through pollution, over-consumption, and in some regions of the world, over-population (Wright & Boorse, 2014). Also attributable to the destruction of a species, are the human activities that result in habitat loss and the introduction of an exotic species into foreign ecosystems (Wright & Boorse, 2014). Human activity is not solely to blame, as each species also has natural predators; however, habitat loss, relating to economic development, appears to be the
This believable mechanism for evolutionary change known as the Natural Selection theory transformed and influenced the views and perspectives of the beginnings of organisms. Darwin and Wallace called this theory ‘natural selection’. Depending on the traits of an organism and whether or not the traits where favourable in its environment, this then
Many communities are impacted by exotic species that are introduced over time (Lankau 2009). These exoctic species can result in either positive or negative effects on the community through interacting with the native species (Lankau 2009). Exotic species are moved by humans outside of their native range; species become invasive when they cause harm to their new environment. Earthworms are exotic in many areas that they are introduced to over time. Earthworms are a major influence on soil composition, but to this day there is still many unknown factors about the species (Zirbes L et.
In the lab, it has been shown that under mechanical stress, the epidermal cells show an increase in the cell cross-sectional area, increased fragmentation of apical microridges, and increased cell proliferation. The cell cross-sectional area and microridge architecture recover as proliferation continues. In the study conducted by Renuka et al. 2016, aPKC morphants show a premature elongation of microridges, where the wildtype ridge length at 27 hpf corresponded to ridge length at 20-22hpf in the has mutants. This increase in length occurs due to an increase in the fusion of shorter microridges, which can be accounted for by the increased crosslinking of actin by the higher levels of phosphomyosin that are localized to the apical domain. Thus, the has mutants have a less fragmented and precociously stable microridge pattern.8 .
Variation is a difference of characteristics such as structure, form, function, colour and size when compared to others of the same species within a specific environment. Variation can occur through mutation, the recombination between chromosomes and migration, of which usually happens due to environmental or genetic factors. Variation permits the survival of species in a changing environment and ensures protection from exposure to diseases or environmental disasters. Those who possess variation in species ensures that when their environment changes the individuals will have the variation that will allow them to survive while those who do not possess the variation will die out. This is natural selection and goes hand in hand alongside variation.
Introduction of Foreign Species into the Australian Ecosystem B1. Investigate the impact of human activities on the diversity of living things. Describe the impact that this activity has on the environment and species diversity. The early European settlers of Australia during the Imperialism introduced feral animals into Australia for many different reasons without knowing the harmful effects it brings to the ecosystem of their new home.