Character Displacement : Abstract and History

Introduction: 

CHARACTER DISPLACEMENT  

Abstract 

• Character displacement has been an important mechanism for enabling closely related species to coexist. 

• But the causes and consequences of character displacement have not yet been fully explored. 
• Character displacement in traits associated with resource use has been studied independently of traits associated with reproduction. 

Introduction 

• Organisms frequently suffer from reduced fitness as a result of interactions with other species that limit access to resources or successful reproduction.  
• Selection minimizes competitive or reproductive interactions between species by favoring the evolution of divergent resource use or reproductive phenotypes. 
• Character displacement is potentially a leading cause of adaptive diversification. 

Character displacement favors the evolution of novel resource use or reproductive traits, drives divergence between sympatric and allopatric conspecific populations, and both initiate and finalize the process of speciation. Despite the significance of character displacement, research has been largely focused on whether it occurs or not. However, it is needed to move beyond establishing the existence of character displacement in order to discover its full implications.  

Research has tended to focus separately on ecological character displacement. There has been little cross-fertilization of ideas among researchers studying these two types of character displacement. Instead of comprehensively reviewing the evidence, we tend to highlight future directions for research in character displacement. 

SPECIFIC GOALS  

There are threefold  

• Seeking to unite ecological and reproductive character displacement under the same conceptual framework. 
• Underscoring the value of exploring more fully the ecological and evolutionary causes and consequences of character displacement. 
• Evaluating how reproductive and ecological character displacement interact and thereby affect the likelihood that either process will unfold. 
• Unifying ecological and reproductive character displacement. Presenting a unified framework for making the fields of ecological and reproductive character displacement parallel in focus. 

• Discussing what constitutes character displacement and review, albeit briefly, the problems of definitions that have plagued both ecological and reproductive character displacement. 
• Suggesting that applying the conceptual framework developed for ecological character displacement to reproductive character displacement will alleviate confusion and place both fields on equal footing.                                         

HISTORY OF CHARACTER DISPLACEMENT  

The term character displacement was coined by Brown and Wilson in 1956. But the idea can be traced to Gause because he showed experimentally that two species cannot stably coexist if they overlap completely in resource requirements. One species ultimately edges out the other in such situations and this is termed as competitive exclusion principle.

It has an important corollary: that species can stably coexist if they differ in resource use. So initially identical, interacting species will experience strong selection to evolve differences in resource use. Similarly, such species will be subjected to strong selection in order to evolve differences in reproductive traits; otherwise, one species may drive the other species extinct locally through “reproductive” exclusion.  

IMPACT OF CHARACTER DISPLACEMENT  

• Character displacement is a general phenomenon in that most species will confront heterospecific species with which they competitively or reproductively interact. 
• Individuals who are most dissimilar to the average resource use or reproductive traits of another species are expected to obtain more resources or have more successful reproduction in such situations than other members of their population. 
• Most divergent individuals should experience the highest fitness consequently.  
• Each species will evolve to be less like the other if heritable variation exists in these traits. 
• Such selection can promote evolutionary divergence in traits associated with resource use or reproduction, i.e., character displacement. 

• Competitive or reproductive exclusion may ensue in absence of character displacement. 

ECOLOGICAL CHARACTER DISPLACEMENT  

Character displacement is the evolutionary emphasizing of phenotypic differences between species as a result of selection to reduce resource competition or reproductive interactions between them. It can assume two distinct forms that differ in the agent and target of selection. “Ecological character displacement” refers to trait evolution that occurs as a result of selection to reduce resource competition between species and thus acts on traits associated with resource use. 

REPRODUCTIIVE CHARACTER DISPLACEMENT  

Contrastingly, reproductive character displacement” refers to trait evolution stemming from selection to lessen sexual interactions between species and therefore acts on traits associated with reproduction. An important prediction is that species should differ in traits associated with resource use or reproduction if they occur together. Only where species co-occur should selection be used to reduce resource competition or reproductive interactions. Populations in sympatry with the heterospecific species should differ from those in allopatry within each specie.

Conclusion 

For closely related species to coexist, character displacement has been a key strategy. Character displacement’s causes and effects, however, have not yet been extensively investigated. Character displacement encourages the development of innovative reproductive or resource-use strategies, promotes population differentiation between sympatric and allopatric conspecific populations, and starts and completes the speciation process. Brown and Wilson introduced the concept of character displacement in 1956. The concept, however, can be attributed to Gause because he demonstrated experimentally that two species cannot coexist stably if their resource requirements totally overlap. It has a crucial implication: species can coexist peacefully even if their methods of resource consumption are different. Character displacement has certain effects like Character displacement occurs frequently in.

FAQs 

1. Why does character displacement occur? 

Ans) Character displacement can occur when two species compete in the same environment. If no adaptation is made to deal with the competition, one species has a higher chance of surviving. 

2. What does character displacement look like in practice? 

Ans) The rituals that lizards use to entice a partner remain the same regardless of the environment they are in. To differentiate themselves from other lizards living in the same environment, they evolve varied coloring. Character displacement can be seen here. 

3. What does “character displacement” mean in biology? 

Ans) Character displacement is the development of different features by two competing species in the same habitat in an effort to reduce conflict between the species. It has been seen with species competing with one another for resources and offspring.