Biogeography Questions And Answers

Sympatric speciation is a process in which new species evolve from a single ancestral species while inhabiting the same geographic region. In order for this process to occur, there must be a mechanism that prevents or reduces interbreeding between individuals of the same population. This mechanism is known as a reproductively isolating mechanism. It can be caused by various factors such as changes in mating behavior, ecological specialization, or chromosomal changes. Therefore, the statement that "something in a population must form a reproductively isolating mechanism" is true, as it is a fundamental requirement for sympatric speciation to take place.

Wegener's Model proposed the concept of continental drift, suggesting that the continents were once joined together in a supercontinent called Pangea and have since drifted apart. This concept was indeed correct, as evidenced by the matching shapes of the continents and the distribution of fossils and rock formations. However, Wegener's model was incorrect in terms of the timing and the processes involved in the drifting apart of the continents.

Extinction occurs when a population or species is unable to adapt or shift their range in response to changes in their environment. This means that they are unable to survive and reproduce successfully, leading to the complete disappearance of the population or species. Therefore, the statement "Extinction represents a failure of a population or species to respond (adapt, shift range) to a changing ecology" is true.

Biological species are commonly inferred from various factors such as genetic variation, morphology, and other genetic characteristics. These factors provide evidence of the diversity and distinctiveness within a particular species. By studying these variations, scientists can classify and define different biological species. Therefore, the statement that biological species are often implied from genetic variation, morphology, genetic variation, etc. is true.

Before the 1960s, biogeography was limited by a "static earth" model of Earth history. This means that scientists believed that the Earth's geography and ecosystems remained relatively unchanged over time. However, advancements in scientific understanding and technology in the 1960s challenged this notion and revealed that the Earth's history is dynamic, with continents shifting, climate changing, and species evolving. This new understanding greatly expanded the field of biogeography and allowed scientists to study the historical movements of species and the factors that shape their distribution patterns.

Vicariance refers to the separation of a population or species into different geographic areas due to the splitting of a landmass or the formation of barriers. Ancestral continents fragmenting is a common cause of vicariance, as it leads to the isolation of populations on separate landmasses. Therefore, it is true to say that vicariance is often associated with ancestral continents fragmenting.

The "Static Earth" model of Earth History required geologically unsupportable land bridges. This means that according to this model, there would need to be land bridges connecting different land masses that are not supported by geological evidence or theories. Therefore, the statement is true as the "Static Earth" model would require land bridges that cannot be supported by geological data.

In parapatric speciation, populations are geographically close to each other but have distinct habitats or niches. This close proximity allows for some gene flow between the populations, but there is also a zone where individuals from the two populations come into contact and interbreed. This zone is known as a hybrid zone, where individuals with mixed genetic characteristics can be found. Therefore, the statement that in parapatric speciation populations have very little geographic separation with areas known as hybrid zones is true.

The statement is true because allopatric speciation refers to the process of speciation that occurs when populations of a species become geographically isolated from each other. In vicariance, a physical barrier such as a mountain range or a river separates the populations, leading to genetic divergence and eventually the formation of new species. Peripheral isolation, on the other hand, occurs when a small population becomes isolated at the periphery of the species' range, often due to dispersal limitations. Both modes of speciation involve geographic isolation and can lead to the formation of new species.

Wegener's evidence of continental and oceanic rocks supported the idea that there was an original supercontinent known as Pangea. This theory suggests that all continents were once connected and have since drifted apart over time. Wegener gathered evidence from the matching shapes of continents, the distribution of fossils, and the similarities in rock formations on different continents. This evidence eventually led to the acceptance of the theory of plate tectonics, which explains the movement of the Earth's lithospheric plates and the formation of continents and oceanic features.

In a cladogram, the only natural groups are monophyletic groups. A monophyletic group consists of a common ancestor and all of its descendants. This means that all members of the group share a common evolutionary history. Any other type of grouping, such as paraphyletic or polyphyletic groups, would not accurately represent the evolutionary relationships among organisms. Therefore, the statement that the only natural groups in a cladogram are monophyletic groups is true.

An electrically diagnosable group is not a possible representation of a species because electrical diagnosis is not a recognized or commonly used method for identifying or classifying species. Morphological diagnosis refers to distinguishing species based on physical characteristics, phylogenetic diagnosis refers to distinguishing species based on evolutionary relationships, and the largest set of reproductively compatible populations refers to a group of individuals that can interbreed and produce viable offspring.

The predictive extinction times increase when birth rate is *low* and the population size is small

The statement "Morphology, genetic variation, etc. imply reproductive isolation" is false. While morphology and genetic variation can be indicators of reproductive isolation, they do not necessarily imply it. Reproductive isolation refers to the inability of individuals from different populations to interbreed and produce fertile offspring. It can be caused by a variety of factors, including geographical barriers, behavioral differences, and genetic incompatibilities. Therefore, while morphology and genetic variation may be related to reproductive isolation, they do not always imply it.

Ecological character displacement refers to the phenomenon where closely related species evolve different traits in response to competition for resources. In the case of Darwin's finches, Hawaiian honeycreepers, and Lake Malawi cichlids, these species have shown variations in beak shape, feeding behavior, and coloration respectively, which are believed to be a result of competition for food resources. This divergence in traits allows them to occupy different ecological niches and reduce competition with each other. Therefore, these examples demonstrate ecological character displacement.

The negative reaction to Wegener's theory can be attributed to several reasons. Firstly, there was not enough geological evidence available at that time to support his theory of continental drift. Additionally, his theory conflicted with preconceived ideas held by many geologists, making it difficult for them to accept his ideas. Furthermore, Wegener's theory contained many factual errors, which further undermined its credibility. Moreover, his theory lacked a plausible mechanism to explain how the continents could move. Lastly, Wegener was not considered to be a 'real geologist' by some, which also contributed to the negative reaction.

Obliquity refers to the tilt of a planet's axis in relation to its orbit around the sun. The given answer options, "High latitude seasonality" and "Difference in low/high latitude radiation," are both results of obliquity. The tilt of the Earth's axis causes the angle of sunlight to vary at different latitudes, resulting in the variation of seasons and the difference in radiation received between low and high latitudes. Therefore, these two options are directly related to the phenomenon of obliquity.

Wegner's evidence for continental drift included the observation that continental rocks (granitic sial) are lighter than oceanic rocks (basaltic sima), which suggests that continents float on the denser oceanic crust. Additionally, the presence of glacial striations provided evidence of past glaciation events that could only be explained by the movement of continents. The fossil record also supported continental drift, as similar fossils were found on different continents that were once connected. Finally, the fluctuations in sea level provided further evidence, as they indicated changes in the positions of continents over time.