Best photography in 1st 2 days in new place
2 songs written on 2 days of new guitar
a
The Origin of Species was first published in 1859. Seven years later, an obscure
monk, Gregor Mendel, published an obscure paper on inheritance in peas that
was not widely noticed until 1900, when it became the foundation of the modern science of genetics. Since then, genetic knowledge has become the chief
framework for describing the processes of evolution within species. This
framework, expressed in both words and equations, describes the factors that
cause genetic changes in species. In the simplest terms: a new version of a gene
(an allele) comes into existence by mutation (usually a change of one of the
units of a DNA sequence). At first it is very rare—only one or a few individuals
carry the allele. If this allele alters a characteristic in such a way as to increase
an individual’s chance of survival or reproduction, it is said to be naturally selected and may become more common because such individuals survive or
reproduce more than those that lack the allele and the advantageous feature.
Perhaps the allele entirely replaces the original form of the gene (the new allele
is fixed), and the population as a whole has a somewhat altered phenotype (i.e.,
characteristic: shorter legs, differently colored bill, different display behavior—whatever feature the gene affects).
a
Dinosaurs aren’t just big, fearsome reptiles; they are a particular clade
(branch) of archosaur reptiles that arose in the early Triassic period, about 240
Ma, and which also include extinct and living crocodiles. (So, crocodiles are
the closest living relatives of birds.) And not all dinosaurs were big (or very
fearsome): some were smaller than chickens
a
The most common basis for evolving altruistic behavior is helping relatives.
a
No comments:
Post a Comment