The Importance of Experimental Studies in Evolutionary Biology

Author(s):  
Douglas J. Futuyma ◽  
Albert F. Bennett
1989 ◽  
Vol 8 (1) ◽  
pp. 3-26 ◽  
Author(s):  
Roger D. Masters

Although men and women often differ in political attitudes and behavior, there is no widely accepted scientific explanation of such phenomena. After surveying evidence concerning gender differences in the fields of social psychology, ethology, neurology, cultural anthropology, and political science, five hypotheses concerning the way males and females respond to social cues are derived from the neo-Darwinian theory of natural selection. The predicted differences in the mode of political cognition are then shown to be consistent with findings from experimental studies of emotional and cognitive reactions to televised facial displays of political leaders.


2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Dovilė Bukauskaitė ◽  
Carolina Romeiro Fernandes Chagas ◽  
Rasa Bernotienė ◽  
Rita Žiegytė ◽  
Mikas Ilgūnas ◽  
...  

Abstract Background Haemosporidian parasites of the genus Haemoproteus (Haemoproteidae) are widespread and cause haemoproteosis in birds and therefore, their diversity, ecology and evolutionary biology have become subjects of intensive research. However, the vectors and transmission patterns of haemoproteids as well as the epidemiology of haemoproteosis remain insufficiently investigated. Several species of Culicoides (Ceratopogonidae) support complete sporogony of haemoproteids belonging to the subgenus Parahaemoproteus. However, experimental research with these fragile insects is difficult to design in the field, particularly because their abundance markedly depends on seasonality. This is an obstacle for continuous sampling of sufficient numbers of naturally infected or experimentally exposed midges from wildlife. We developed simple methodology for accessing sporogonic development of haemoproteids in laboratory-reared Culicoides nubeculosus. This study aimed to describe the mosaic of methods constituting this methodology, which was applied for investigation of the sporogonic development of Haemoproteus (Parahaemoproteus) pastoris, a widespread parasite of the common starling Sturnus vulgaris. Methods The methodology consists of the following main stages: (i) laboratory rearing of C. nubeculosus from the egg stage to adult insects; (ii) selection of naturally infected birds, the donors of mature gametocytes to expose biting midges; (iii) experimental exposure of insects and their laboratory maintenance; and (iv) dissection of exposed insects. Biting midges were exposed to H. pastoris (cytochrome b lineage hLAMPUR01) detected in one naturally infected common starling. Engorged insects were dissected at intervals in order to follow sporogony. Microscopic examination and PCR-based methods were used to identify the sporogonic stages and to confirm the presence of the parasite lineage in infected insects, respectively. Results Culicoides nubeculosus females were successfully reared and exposed to H. pastoris, which completed sporogonic development 7–9 days post-infection when sporozoites were observed in the salivary glands. Conclusions The new methodology is easy to use and non-harmful for birds, providing opportunities to access the sporogonic stages of Parahaemoproteus parasites, which might be used in a broad range of parasitology and genetic studies. Culicoides nubeculosus is an excellent experimental vector of subgenus Parahaemoproteus and is recommended for various experimental studies aiming investigation of sporogony of these pathogens.


2021 ◽  
Vol 71 ◽  
pp. 249-270
Author(s):  
Simon Pierce ◽  
Jason D. Fridley

John Philip ‘Phil’ Grime developed fundamental theory in plant ecology that emerged from a lifetime of fieldwork and experimental studies in the Sheffield region, South Yorkshire, UK. His approach was an unusual combination of observation, experiment and theory: he conducted detailed, intensive observations of natural communities, alongside experimental manipulation of those communities and simulated ‘microcosms’ in the service of formulating general rules (‘strategies’) by which plants evolve with respect to their environment. In this way, Grime was one of several key figures that propelled plant ecology away from descriptive methods focusing on vegetation composition and toward a science more integrated with other fields, including evolutionary biology and Earth science. Grime's investigative approach was an inspiration for the modern field of global change biology, and, by focusing on understanding the contrasting roles species and their traits play in the functioning of ecosystems, marked the beginning of the field of plant functional ecology. For much of his career Grime held the post of full professor (and in retirement, emeritus professor of ecology) at the University of Sheffield, where he also served as the director of the Unit of Comparative Plant Ecology and of the Buxton Climate Change Impacts Laboratory. Awarded an honorary doctorate by Radboud University (Nijmegen, The Netherlands) and a foreign membership of the Royal Netherlands Academy of Arts and Sciences, Grime was the first person awarded the Alexander von Humboldt Award of the International Association for Vegetation Science.


2007 ◽  
Vol 4 (16) ◽  
pp. 819-829 ◽  
Author(s):  
Andrew J.K Conlan ◽  
Christopher Coward ◽  
Andrew J Grant ◽  
Duncan J Maskell ◽  
Julia R Gog

Campylobacter jejuni is one of the most common causes of acute enteritis in the developed world. The consumption of contaminated poultry, where C. jejuni is believed to be a commensal organism, is a major risk factor. However, the dynamics of this colonization process in commercially reared chickens is still poorly understood. Quantification of these dynamics of infection at an individual level is vital to understand transmission within populations and formulate new control strategies. There are multiple potential routes of introduction of C. jejuni into a commercial flock. Introduction is followed by a rapid increase in environmental levels of C. jejuni and the level of colonization of individual broilers. Recent experimental and epidemiological evidence suggest that the celerity of this process could be masking a complex pattern of colonization and extinction of bacterial strains within individual hosts. Despite the rapidity of colonization, experimental transmission studies exhibit a highly variable and unexplained delay time in the initial stages of the process. We review past models of transmission of C. jejuni in broilers and consider simple modifications, motivated by the plausible biological mechanisms of clearance and latency, which could account for this delay. We show how simple mathematical models can be used to guide the focus of experimental studies by providing testable predications based on our hypotheses. We conclude by suggesting that competition experiments could be used to further understand the dynamics and mechanisms underlying the colonization process. The population models for such competition processes have been extensively studied in other ecological and evolutionary contexts. However, C. jejuni can potentially adapt phenotypically through phase variation in gene expression, leading to unification of ecological and evolutionary time-scales. For a theoretician, the colonization dynamics of C. jejuni offer an experimental system to explore these ‘phylodynamics’, the synthesis of population dynamics and evolutionary biology.


2019 ◽  
Vol 50 (1) ◽  
pp. 335-354 ◽  
Author(s):  
David N. Reznick ◽  
Joseph Travis

Guppies in Trinidad range across aquatic environments with fish communities that vary in risk of predation. These communities are often discrete, separated by waterfalls, with high-predation communities downstream and low-predation communities upstream. This gradient is repeated in many rivers; in each one, we see the same divergence between guppy populations in life history, behavior, morphology, and physiology. We have shown that the agent of selection on the life history, behavior, and physiology in low-predation communities is high population density and the cascade of ecological effects that stems from it. In effect, guppy populations modify their ecosystem and, in so doing, impose selection on themselves and shape their own evolution, which further changes the ecosystem. Evolution unfolds rapidly in this system, which has enabled us to study the dynamics of the process, not just its end points. Those studies enable us to answer some very general questions in ecology and evolutionary biology.


Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 1071-1085 ◽  
Author(s):  
John K Kelly

Abstract Deleterious mutations are relevant to a broad range of questions in genetics and evolutionary biology. I present an application of the “biometric method” for estimating mutational parameters for male fitness characters of the yellow monkeyflower, Mimulus guttatus. The biometric method rests on two critical assumptions. The first is that experimental inbreeding changes genotype frequencies without changing allele frequencies; i.e., there is no genetic purging during the experiment. I satisfy this condition by employing a breeding design in which the parents are randomly extracted, fully homozygous inbred lines. The second is that all genetic variation is attributable to deleterious mutations maintained in mutation-selection balance. I explicitly test this hypothesis using likelihood ratios. Of the three deleterious mutation models tested, the first two are rejected for all characters. The failure of these models is due to an excess of additive genetic variation relative to the expectation under mutation-selection balance. The third model is not rejected for either of two log-transformed male fitness traits. However, this model imposes only “weak conditions” and is not sufficiently detailed to provide estimates for mutational parameters. The implication is that, if biometric methods are going to yield useful parameter estimates, they will need to consider mutational models more complicated than those typically employed in experimental studies.


Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.


2000 ◽  
Vol 15 (3) ◽  
pp. 211-222 ◽  
Author(s):  
Alan R. Templeton ◽  
Stephanie D. Maskas ◽  
Mitchell B. Cruzan

Sign in / Sign up

Export Citation Format

Share Document