Polygenetic Traits

What are Polygenetic Traits? 


Polygenic traits are traits that are controlled by more than one gene.  For example, height, weight, hair color, skin color (basically anything dealing with color). This allows for a wide range of physical traits. 


One good example of these traits is, if height was controlled by one gene A and if AA = 6' and Aa = 5'7" and as = 5', then people would either be 6', 5'7", or 5'. Since height is controlled by more than one gene, a wide range of heights is possible.


Polygenic traits usually produce a continuum of phenotypes.  Individual genes of a polygenic trait follow Mendel's laws, but together do not produce Mendelian ratios.  A bell shaped curve often describes the distribution of phenotypic classes of a polygenic trait.



They are recognized by their expressions that result from gradation of continuous variation.
Additive effects of two or more separate pair of genes control continuous variation.
The traits are quantified by measuring the variation, rather than counting.

They're different types of phenotypic expression which contributes to different pairs of genes.
These traits are also known as quantitative traits or multifactorial traits.  They are controlled by two or more genes at different loci on different chromosomes or it is the trait that is controlled by non-allelic genes. They are known as quantitative traits as their phenotypic expression is dependent on multiple alleles located on different chromosomes.

Phylogeny

Phylogeny is the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms.
Phylogeny proposes that plants or animals of different species descended from common ancestors. The are a huge number of species that have ever lived are extinct, and relatively few of their remains have been preserved in the fossil record. Most phylogenies therefore are hypotheses and are based on indirect evidence. There is universal understanding that the tree of life is the result of organic descent from earlier ancestors and that true phylogenies are discoverable.

Evidence for specific phylogenies

Most of the data used in making phylogenetic judgments have come from comparative anatomy and from embryology, although these are rapidly being surpassed by systems constructed using molecular data. In comparing features common to different species, anatomists try to distinguish between homologies, or similarities inherited from a common ancestor, and analogies, or similarities that arise in response to similar habits and living conditions.


By counting differences in the sequence of units that make up protein and deoxyribonucleic acid (DNA) molecules, researchers have devised a tool for measuring the degree to which different species have diverged since evolving from a common ancestor. Because mitochondrial DNA has very high mutation rates compared with nuclear DNA, it has been useful for establishing relationships among groups that have diverged recently. Essentially, the application of molecular genetics to systematics is similar to the use of radioisotopes in geologic dating: molecules change at different rates, with some, such as mitochondrial DNA, evolving rapidly and others, such as ribosomal RNA, evolving slowly. An important assumption then in using molecules for phylogeny reconstruction is to select the appropriate gene for the age of the taxon under study.

Sustainability

Sustainability is how biological systems endure and remain diverse and productive. Sustainability refers to the endurance of systems and processes. The organizing principle for sustainability, is sustainable development, which includes the four interconnected domains, ecology, economics, politics and culture. 


Sustainability science is the study of the concepts of sustainable development and environmental science.


Healthy ecosystems and environments are necessary to the survival of humans and other organisms. Ways of reducing human impact are environmentally-friendly chemical engineering, environmental resources management and environmental protection.


Moving towards sustainability is also a social challenge that entails international and national law, urban planning and transport, local and individual lifestyles and ethical consumerism. Ways of living more sustainably can take many forms from re-organizing living conditions.


Despite the increased popularity of the use of the term "sustainability", the possibility that human societies will achieve environmental sustainability has been, and continues to be, questioned—in light of environmental degradation, climate change, overconsumption, and societies' pursuit of indefinite economic growth in a closed system.


Sustain can mean “maintain", "support", or "endure”.  Since the 1980s sustainability has been used more in the sense of human sustainability on planet Earth and this has resulted in the most widely quoted definition of sustainability as a part of the concept sustainable development, that of the Brundtland Commission of the United Nations on March 20, 1987: “sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”