Introduction to Animal Structure and Function Adaptation Body Plans Tissues Organs Organ Systems Biology 1107 Lecture 15 Lecture 15 Overview 2 45 Overview Anatomy and physiology 3 Overview Adaptation 4 Limitations on adaptations 5 8 Genetics 5 Existing morphology 6 Physical laws 7 Trade offs 8 Adaptation vs acclimatization acclimation 9 Form structure and function correlations 10 13 Darwin Finch beak and food type example 11 Stickleback Fish body armor and predation example 12 Evidence on a molecular and cellular level 13 Body plans 14 22 Surface area volume relationships 14 15 Single celled organisms and environment exchange 16 Simple body plans and environment exchange 17 Complex body plans and environment exchange 18 Adaptive surface area and exchange modifications 19 22 Tissues organs organ systems 23 42 Organ systems 24 25 Tissue types 26 38 Epithelial 27 28 Connective types 29 33 Muscle types 34 37 Nervous 38 Hierarchical organization of bodies 39 Endocrine vs nervous system signaling and body coordination 40 42 Introduction Anatomy is the study of an organism s physical structure 3 45 Physiology is the study of how the physical structures in an organism function Desert hare Form Function and Adaptation There is a great amount of diversity in anatomical and physiological traits observed in animals Males low coloration 4 45 Biologists who study animal anatomy and physiology are studying adaptations Adaptations are heritable traits that allow individuals to survive and reproduce in a certain environment better than individuals that lack those traits e g guppy coloration Adaptation results from evolution by natural selection Natural selection favors those variations in a population that increase relative fitness fitness the production of offspring Biologists who study anatomy and physiology study compromise and constraint as well as adaptation High predation Males high coloration Low predation 5 45 Limitations on Adaptations Adaptations are limited by many factors Genetics Natural Selection can only act on pre existing variation within a population New mutations must arise and be expressed in the phenotype in order for traits to be exposed to selection In this hypothetical population a new mutation arises that allows an individual to have better camouflage from predators thus this individual is better adapted to the environment and will produce more offspring Generation 1 Generation 2 Generation 3 Limitations on Adaptations Adaptations are limited by many factors Existing Morphology Current morphology may limit the directions of future evolutionary change i e historical contingency 6 45 The evolution of the vertebrate eye has resulted in a structure with a blindspot compared to the independently evolved cephalopod eye e g octopus 7 45 Limitations on Adaptations Adaptations are limited by many factors Physical Laws Laws of physics e g drag or locomotion make some adaptive solutions more likely than others many times leading to convergent evolution similar adaptations in distantly related organisms Water is denser than air thus any protruding structures on an organism would impede its ability to swim quickly This property of water limits the possible shapes for animals that are fast swimmers Many types of aquatic animals have converged on a streamlined fusiform tapered body plan 8 45 Limitations on Adaptations Adaptations are limited by many factors Trade offs Inescapable compromises between traits e g trade off between quality and quantity of offspring Trade offs may be the most important constraint on adaptations because trade offs are pervasive common in nature Researchers investigated the predicted trade off between egg size and egg number clutch size by manipulating these parameters in side blotched lizards Their results showed that such a trade off does indeed exist lizards either produce few large high quality eggs or many small low quality eggs Side blotched lizard Adaptation vs Acclimatization 9 45 Adaptation is a genetic change that occurs over generations within a population in response to natural selection Acclimatization or acclimation is a phenotypic change that occurs within an individual in response to a short term change in environmental conditions The immediate process of an animal acclimating is not adaptation BUT the ability to acclimate is itself an adaptation Form Function and Adaptation 10 45 If a structure found in an animal is adaptive meaning that it helps the individual survive and produce offspring it is common to observe that the structure s size shape or composition correlates closely with its function The mechanism responsible for correlations between structure and function can be straightforward If a mutant allele alters a structure such that it functions more efficiently individuals with that allele will have greater fitness i e more offspring resulting in an increased frequency of the allele in the population over time Form Function and Adaptation Galapagos Finches Changes in the alleles of genes that affect beak development have resulted in speciation and specialization on different food sources Some alleles produce high beak growth others produce little beak growth 11 45 12 45 Form Function and Adaptation Stickleback Fish Heavily armored marine stickleback have repeatedly invaded freshwater habitats with and without piscivorous predators Those population inhabiting lakes without piscivorous predators typically lose much of their antipredator morphology spines body armor over time because it is otherwise costly to maintain Alleles of certain genes are responsible for production of body armor and spines and the frequency of these alleles in the high predation low predation populations differ 13 45 Structure Function Correlation In Molecules and Cells Correlations between form and function start at the molecular level For example protein shape correlates with their role as enzymes structural components of the cell or transporters Similar correlations between structure and function occur at the level of the cell For example cells that secrete digestive enzymes contain a lot of rough ER and Golgi apparati these cells must synthesize many enzymes and secrete them Likewise cell shape and function correlate For example absorptive cells have a large surface area e g microvilli are cytoplasmic protrusions 14 45 Body Plans Simple vs Complex The rate at which gases nutrients and waste products diffuse across membranes depends in part on the amount of