<span>Cladistic analysis is a popular method for reconstructing evolutionary relationships on the human lineage. However, it has limitations and hidden assumptions that are often not considered by palaeoanthropologists. Some researchers who are opposed to its use regard cladistics as the preferred method for taxonomic "splitters" and claim it has lead to a revitalisation of typology. Typology remains a part of human evolutionary studies, regardless of the acceptance or use of cladistics. The assumption/preference for "splitting" over "lumping" in cladistics (alpha) taxonomy and the general failure to evaluate (post-hoc) such taxonomies have served to reinforce this assertion. Researchers have also adopted a number of practices that are logically untenable or introduce considerable error. The evolutionary trend of human encephalisation, apparently isometric with body size, and concurrent reduction in the gut and masticatory apparatus, suggests continuous cladistic characters are biased by problems of body size. The method suffers a logical weakness, or circularity, leading to bias when characters with multiple states are used. Coding of such characters can only be done using prior criteria, and this is usually done using an existing phylogenetic scheme. Another problem with coding character states is the handling of variation within species. While this form of variation is usually ignored by palaeoanthropologists, when characters are recognised as varying, their treatment as a separate state adds considerable error to cladograms. The genetic proximity of humans, chimpanzees and gorillas has important implications for cladistic analyses. It is argued that chimpanzees and gorillas should be treated as ingroup taxa and an alternative outgroup such as orangutans should be used, or an (hypothetical) ancestral body plan developed. Making chimpanzees and gorillas ingroup taxa would considerably enhance the biological utility of anthropological cladograms. All published human cladograms fail to meet standard quality criteria indicating that none of them may be considered reliable. The continuing uncertainty over the number and composition of fossil human species is the largest single source of error for cladistics and human phylogenetic reconstruction.
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Genotype
DEFINITION
IT IS THE GENETIC MAKEUP OF THE CELLS.
Phenotype
DEFINITION
IT IS PHYSICAL APPEARANCE OF ORGANISMS.
The Genotype, carried by all living organisms, holds the critical instructions that are used and interpreted by the cellular machinary of the cells to produce the r Phenotype of the organism.
Thus, all the physical parts, the molecules, cells and other structures, are built and maintained by cells following the instructions give by the genotype.
Your nervous system quickly responds to the threat and sends a signal to your brain which causes your muscles/ body to react.
HOPE THIS HELPS!
Answer:
genetic variation
Explanation:
Genetic variation refers to the difference in genetic content of organisms within a population. The genetic makeup of living organisms are made up of GENES, which exists in contrasting pairs called ALLELES. Each allele is responsible for variation in traits exhibited by the organisms. Differences in the allelic content of organisms of the same species leading to the display of varying phenotypic characteristics is referred to as GENETIC VARIATION.
This is the case in the example given in which four birds in a population possess a range of wing and feather colors i.e light brown feathers with darker wings, dark feathers with lighter wings, medium brown feathers with light wings, and medium brown feathers with very dark wings, all resulting from a variation in their genetic content. Hence, this is an example of GENETIC VARIATION.
Germs are transferred from one bacteria to the next....