How does the earths life change over time

How does the earth’s life change over time? -- biological evolution: the process whereby earth’s life changes over time through changes in the genetic characteristics of populations -- theory of evolution: all species descended from earlier, ancestral species

Genetics review • The phenotype is the outward expression of an individual's genotype • • • Genotype: unique genetic constitution Phenotype: outward expression of that genotype A genotype = set of genetic instructions; blueprints Phenotype = the expression of that genotype in the form of an organism (is that enough? Are there external factors? ) • Effects of environmental influences are like details in a blueprint that are left to the discretion of the building contractor. . What does that mean?

More genetics • All phenotypic traits have: • Genetic basis + influence by variations in the environment • What kind of environmental variations? • Phenotypic plasticity • Capacity of an individual to exhibit different responses to its environment • How the individual responds to environmetnal variation

Sources of genetic variation • How does genetic variation arise? • Mutation • Any change in the sequence of the nucleotides that make up a gene or in regions of the DNA that control the expression of a gene • Consequence? • Drastic – maybe lethal – changes in the phenotype • No detectable effect – silent mutations • New phenotypes produced better suited to the local environment phenotypes increase • Multiple effects pleiotropy (effects of a single gene on multiple traits) Also: Gene Flow (any movement of genes from one population to another) and Sex (genetic shuffling)

Mechanisms of change • Mutation • Migration • Genetic drift • Natural selection

Genetic basis of continuously varying phenotypic traits • Many phenotypic traits with ecological relevance vary continuously over a range of values (eg: body size)

Adaptations result from natural selection on heritable variation in traits that effect evolutionary fitness • The most important consequence of genetic variation for the study of ecology is evolution by natural selection • Evolution • Any change in a population’s gene pool (what is a gene pool? ) • Individuals whose traits enable them to have higher rates of reproduction have more offspring alleles increase • Adaptations or evolutionary adaptation • Process = adaptation

Adaptation (process of evolution by natural selection) 1. Variation among individuals • Eg – bird beaks; different individuals have different-sized beaks 2. Inheritance of that variation • Size of bird’s beak has an existence of its own in a population; individual is borrowing that trait 3. Differences in survival and reproductive success (or fitness) related to that variation • Fitness: production of descendants over an individual’s lifetime.

+ Evolutionary change Change in a California citrus pest Cyanide fumigation no longer effective

So what is evolution? By: Andrew A. Forbes (Dept. of Biology, University of Iowa) & Billy A. Krimmel (Dept. of Entomology, University of California at Davis) © 2010 Nature Education • Evolution Is Change in the Inherited Traits of a Population through Successive Generations • The geneticist Theodosius Dobzhansky (1964) famously wrote "nothing in biology makes sense except in the light of evolution. ” Same applies to Ecology

What is not evolution? • (1) evolution does not progress toward an ultimate or proximate goal (Gould 1989). Evolution is not "going somewhere"; it just describes changes in inherited traits over time. Occasionally, and perhaps inevitably, this change results in increases in biological complexity, but to interpret this as "progress" is to misunderstand the mechanism. • (2) evolution and natural selection are not equivalent terms. Natural selection is one force that can drive and influence evolutionary change, but other mechanisms can be equally important

Micro evolution vs Macro evolution • microevolution (change below the level of the species) • macroevolution (change above the level of the species). • Population ecologists, conservation biologists, and behavioral ecologists are most directly concerned with microevolutionary processes. • shifts in the values and frequencies of particular traits among members of populations • can, but do not necessarily, lead to the formation of new species over time but instead result in fluctuating frequencies of traits within populations tracking ever-changing selective pressures • Since some microevolutionary processes may occur over just a few generations, they can often be observed in nature or in the laboratory.

Macro evolution Micro evolution

• Natural selection: individuals with certain traits are more likely to survive and reproduce under a particular set of environmental conditions than are those without the trait • cooperation • Biological evolution through natural selection explains how life has changed over the past 3. 5 billion years

Isn’t evolution just a theory? • https: //www. youtube. com/watch? v=85 di. EXb. JBIk

Questions on CC: • How will certain organisms of different species co-evolve with the new circumstances of a changing climate? How do certain organisms that are in a symbiotic relationship evolve with one another and often wonder how changes in climate and temperature will affect them? • What are solutions by “common people”; how to lessen the inevitable? • How will it influence Homo Sapiens from an evolutionary perspective? • Which species will have the least problem adapting to the aftermath? What species will suffer the most? • What are the main contributing factors for climate change? • What are the serious repercussions that might happen to Lebanon if we don’t stop this crisis? How will we - as Lebanese - be affected? Will our country still exist if the sea level rises ? Will new diseases appear from a medical point of view ? • What areas will be least affected?

Heavy rains during El Nino events support lush plant growth in the archipelago.

What does this mean? • Finches do not survive or die at random • Because the average hardness of seeds increased as the drought intensified and the softest seeds were consumed birds with larger beaks that could generate the forces needed to crack hard seeds survived better than those with smaller beaks • The average beak size of surviving individuals and their progeny increased significantly • What is necessary for such ‘evolution in action’?

What do they tell us about evolution?

Want more ‘evolution in action’?