Concept explainers
To describe: The comparison and differences between Haeckel’s and Von Baer’s ways of thinking about changes in development over the course of animal evolution.
Introduction: Biologists from the nineteenth and twentieth centuries compared and described embryonic development of a diverse group of animals. They also described the ways in which the various morphogenetic processes in different groups of organisms result in different adult forms.
Explanation of Solution
Among the many first things, the biologists who were studying developmental biology learned that the embryos of many species are more often similar than the adults. Both Karl Von Baer and Ernst Haeckel studied embryo development to know more about the developmental pattern of organisms. In 1882, Karl von Baer noted that those features that are common to higher taxon appear early than those characters of lower tax such as families or order. According to Baer’s law, embryo development passes through the developmental stages of their adults. Haeckel also explained that the development of an organism, during the course of evolution, pass through all its adult form’s developmental stages.
Following are some differences in the way of thinking of these two biologists about changes in an organism’s development over the course of evolution:
To explain: The learning about phylogeny from development, even though Haeckel’s dictum seldom holds.
Introduction: Biologists from the nineteenth and twentieth century compared and described embryonic development of a diverse group of animals. They also described the ways in which the various morphogenetic processes in different groups of organisms result in different adult forms.
Explanation of Solution
Ernst Haeckel, a German biologist, interpreted developmental patterns to mean that an individual organism’s development repeats the evolutionary history of adult forms of their ancestors. It is known as “ontogeny recapitulates phylogeny”.
However, by the end of the 19th century, it was clear that Haeckel’s dictum seldom holds. For example, embryos of mammal and reptile go through a development stage where they have pharyngeal clefts and branchial arches identical to fish supporting that they share a common ancestor with fish. However, mammals and reptiles never acquire the characters of typical adult fish.
Nevertheless, these developmental studies provided information about the evolutionary relationship between different organisms. By studying embryo development, biologists identified many common developmental difference patterns among species.
Want to see more full solutions like this?
- In the late 1800s, a biologist studying animal embryos coined the phrase “ontogeny recapitulates phylogeny,” meaning that the physical development of an animal embryo (ontogeny) seemed to retrace the changing form of the species during its evolutionary history (phylogeny). Why would embryonic development retrace evolutionary steps?arrow_forwardCan convergent (or parallel) evolution of similar morphology in two different lineages involve DNA sequence evolution in different parts of the same developmental gene? Explain how.arrow_forwardDraw a phylogenetic reconstruction for the hypothetical frog species. Once you have a cladogram you feel confident about, use lines and labels on cladogram to indicate where character states hanged. How many evolutionary changes occurred in your phylogeny? Is there evidence of an evolutionary convergence having occurred in your phylogeny? How about evolutionary reversals?arrow_forward
- The figure shows a phylogenetic tree of various members of the order Proboscidea, which includes modern elephants. Which of the following claims is best supported by the information in the figure ? a.The mastodon and the Stegodon diverged from their common ancestor 22 million years ago. b.The common ancestor of the African elephant and the mastodon is the Palaeomastodon. c.The mammoth diverged from its most recent common ancestor with African elephants before the mastodon diverged from its most recent common ancestor with Stegodons. d.The Asian and African elephants are the most closely related species shown on the tree.arrow_forwardA study inferred a maximum likelihood phylogenetic tree based on sequence data from a specific gene. Numbers represent bootstrap support values for each clade. Based on the study's findings, how certain should we be that marsupials are sister to placental mammals, rather than monotremes? What number is used to represent this certainty, and how was it calculated?arrow_forwardcreate a phylogeny of human evolution. It should include all known hominids beginning with the earliest and ending with modern Homo sapiens. In your version of a future, humans will create a phylogeny of human evolution. It should include all known hominids beginning with the earliest and ending with modern Homo sapiens and your version of a future human. The requirement is to put the genus and species name of the hominid, beginning with the earliest one, which is Sehelanthropus tchadensis, in the phylogeny along with its dating age.arrow_forward
- How do modern evolutionists view the relationship between ontogeny and phylogeny? Explain how the observation of paedomorphosis conflicts with Haeckel’s “biogenetic law.”arrow_forwardThe phylogenetic tree for vertebrates depicted below was constructed from sequence data for two rRNA mitochondrial genes (12S and 16S). How do the results of this analysis compare with the phylogenetic trees in Figures 32.10 and 32.24? Identify the major clades of vertebrates on the tree depicted below. Source: R. Zardoya and A. Meyer. 1998. Complete mitochondrial genome suggests diapsid affinities of turtles. Proceedings of the National Academy of Sciences, USA 95:1422614231. Copyright 1998 National Academy of Sciences, U.S.A.arrow_forwardThe phylogenetic tree for 12 cat species (Felidae) reproduced at right was assembled from molecular sequence data. Which species is the domestic cats closest relative? Which clade is the sister taxon to tigers? Are bobcats more closely related to cougars or to ocelots? Source: From Warren E. Johnson et al. 2006. The late Miocene radiation of modern Felidae: A genetic assessment. Science 311:7377.arrow_forward
- Genomics and Human Evolution The Denisovan genome contains sequences that originated from an unknown human species. Using Figure 19.11, speculate on which species this might be. Is it possible that there are other ancestral species that may remain to be discovered that would change the phylogeny presented in the figure? FIGURE 19.11 Estimates for the dates of origin and extinction for the three main groups of hominins (green, blue, and orange). The australopithecines split into two groups about 2.7 million years ago. One of those groups, the genus Homo, contains the ancestors to our species, H. sapiens.arrow_forwardINTERPRET DATA Which of the primates in Figure 18-18 is the most distantly related to humans? Explain your answer. Figure 18-18 Differences in DNA nucleotide sequences as evidence of evolutionary relationships Comparing the same gene in different organisms provides a window into evolution. Here the differences in the non-protein-coding region of the -globin gene are compared between humans and other primates. Evolutionary biologists are rapidly expanding such studies from comparing one or several genes to comparing entire genomes.arrow_forwardStructures in two different species may be similar because of either of two very different reasons. Describe these two reasons. You must use all four of the following terms in your explanation: homologous structures, analogous structures, convergent evolution, and divergent evolutionarrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage LearningBiology Today and Tomorrow without Physiology (Mi...BiologyISBN:9781305117396Author:Cecie Starr, Christine Evers, Lisa StarrPublisher:Cengage LearningBiology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning