The Community of Ecological Opportunities

Author(s):  
Mark A. McPeek

This chapter examines ecological opportunities that are available to species in various positions within a biological community, with particular emphasis on identifying the criteria necessary for an ecological opportunity to exist. Before discussing what performance capabilities a species must have to fill different types of ecological opportunities and what is required for invasibility of species into different functional positions in a community, the chapter considers the different frameworks that have been used to model species interactions. It then describes resource and apparent competition to show how resource availability from below and predation pressure from above can affect the types of species that can exploit specifc ecological opportunities. It also analyzes communities with three trophic levels, intraguild predation or omnivory, mutualism, the mechanisms that foster coexistence between one plant species and one pollinator species, and the case of one plant species with multiple pollinators.

2021 ◽  
Vol 118 (12) ◽  
pp. e2023872118
Author(s):  
Ignasi Bartomeus ◽  
Serguei Saavedra ◽  
Rudolf P. Rohr ◽  
Oscar Godoy

Ecological theory predicts that species interactions embedded in multitrophic networks shape the opportunities for species to persist. However, the lack of experimental support of this prediction has limited our understanding of how species interactions occurring within and across trophic levels simultaneously regulate the maintenance of biodiversity. Here, we integrate a mathematical approach and detailed experiments in plant–pollinator communities to demonstrate the need to jointly account for species interactions within and across trophic levels when estimating the ability of species to persist. Within the plant trophic level, we show that the persistence probability of plant species increases when introducing the effects of plant–pollinator interactions. Across trophic levels, we show that the persistence probabilities of both plants and pollinators exhibit idiosyncratic changes when experimentally manipulating the multitrophic structure. Importantly, these idiosyncratic effects are not recovered by traditional simulations. Our work provides tractable experimental and theoretical platforms upon which it is possible to investigate the multitrophic factors affecting species persistence in ecological communities.


2019 ◽  
Author(s):  
xiangping wang ◽  
Tong Zeng ◽  
Meihong Wen ◽  
Mingsong Wu ◽  
Dianxiang Zhang

Abstract Background: The seasonal dynamics of plant and pollinator species components in the community could influence the structure of plant-pollinator networks. However, such dynamics are seldom been attention for oceanic islands networks. Here, we estimated the seasonal variation of seven plant-pollinator networks in Yongxing Island community. We collected a two-monthly data for each network of four seasons and used temporally discrete networks to characterize seasonal changes in plant-pollinator interactions. We predicted that greater floral resource availability in the season would allow for higher specialization patterns as previously described across large spatial gradients, with finer partitioning of the floral niche by the pollinators. Results: As we expected, we found that rainy season network with more plant species in bloom, showed higher levels of network-wide specialization and modularity. However, when we compared seven targeted sampling networks, both the network-wide specialization and modularity were negatively correlated with the number of plant species in bloom. There were no differences between rainy and dry seasons and among four seasons in species-level indices, suggesting that higher network level specialization may be an emergent property only seen when considering the entire network. Hawkmoths presented higher values of specialization in relation to other functional groups; and Apidae presented higher values of species strength than other functional groups. These results suggest some specialized plant species are visited only by Hawkmoths, and most plants associated with Apidae are used by this group. Conclusions: Our results suggested that, on oceanic island, increased floral resource availability in the season may not promote lower interspecific competition among pollinators leading to increased niche overlap, thus explaining the decreased in specialization. Plant-pollinator interactions data collection during dry, rainy season and all year-round generates lower network specialization than four seasons, and this may because that most pollinator species activity spans longer periods than a single season on islands. Thus, depending on the period of data collection, different networks structure of interaction may be found. Plant-pollinator networks have structural properties that vary according to seasons, and this should be taken into account in the studies of complex systems of interactions between plants and pollinators in oceanic islands communities.


Author(s):  
Mark A. McPeek

This chapter explores the evolutionary dynamics that arise when different types of species mix together in a community either by invasion or by perturbation, as well as community mixing caused by climate change. In particular, it considers the features that promote or retard ecological differentiation of species. The chapter first describes a general model of evolutionary and ecological dynamics in a community before discussing adaptive differentiation at multiple trophic levels. It then examines differentiation of species with identical underlying parameters vs. different underlying parameters, along with intraguild predation and how ecological opportunity evolves within biological communities. It also investigates when neutral species will initially differentiate from one another to convert them into a set of coexisting species, and when differentiated species will initially converge to become ecologically more similar. The chapter shows that, when differentiation occurs, the type of traits underlying species interactions determine the ecological structure of the resulting community.


Oecologia ◽  
2021 ◽  
Vol 195 (1) ◽  
pp. 213-223
Author(s):  
Mark A. Lee ◽  
Grace Burger ◽  
Emma R. Green ◽  
Pepijn W. Kooij

AbstractPlant and animal community composition changes at higher elevations on mountains. Plant and animal species richness generally declines with elevation, but the shape of the relationship differs between taxa. There are several proposed mechanisms, including the productivity hypotheses; that declines in available plant biomass confers fewer resources to consumers, thus supporting fewer species. We investigated resource availability as we ascended three aspects of Helvellyn mountain, UK, measuring several plant nutritive metrics, plant species richness and biomass. We observed a linear decline in plant species richness as we ascended the mountain but there was a unimodal relationship between plant biomass and elevation. Generally, the highest biomass values at mid-elevations were associated with the lowest nutritive values, except mineral contents which declined with elevation. Intra-specific and inter-specific increases in nutritive values nearer the top and bottom of the mountain indicated that physiological, phenological and compositional mechanisms may have played a role. The shape of the relationship between resource availability and elevation was different depending on the metric. Many consumers actively select or avoid plants based on their nutritive values and the abundances of consumer taxa vary in their relationships with elevation. Consideration of multiple nutritive metrics and of the nutritional requirements of the consumer may provide a greater understanding of changes to plant and animal communities at higher elevations. We propose a novel hypothesis for explaining elevational diversity gradients, which warrants further study; the ‘nutritional complexity hypothesis’, where consumer species coexist due to greater variation in the nutritional chemistry of plants.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species’ interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.


1992 ◽  
Vol 70 (3) ◽  
pp. 642-650 ◽  
Author(s):  
Raymond Louis Tremblay

Reduction in the number of pollinator species per plant species is a mechanism that may lower the cost of pollen transfer. Using efficient pollinators may have an evolutionary significance. It is hypothesized that an evolutionary trend from many pollinators to few pollinators per plant species should be observable when species from ancestral versus recently derived monophyletic taxon are compared. Three different orchid phylogenetic sequences are used; two of the phylogenies show a reduction in the number of pollinator species per orchid species from the most ancestral to the most recently derived subfamilies. The third classification did not show this trend. It is thus possible to observe macroevolution of pollinator specialization of a monophyletic plant taxon. Key words: evolution, pollination, systematics, Orchidaceae, evolutionary ecology.


2013 ◽  
Vol 85 (4) ◽  
pp. 1449-1460 ◽  
Author(s):  
MAINARA F. CASCAES ◽  
VANILDE CITADINI-ZANETTE ◽  
BIRGIT HARTER-MARQUES

Phenological studies assist in forest ecosystems comprehension and evaluation of resource availability for wildlife, as well as in improving the understanding of relationships between plants and their pollinators and dispersers. This study aims to describe the reproductive phenophases of riparian plant species and correlate them with climatic variables. The reproductive phenology was analyzed biweekly throughout one year, recording the absence or presence of flowers/fruits. The flowering phenophase occurred throughout the year, with an increase in number of species in blossom in October, November, and December. The flowering peak of the community was observed in November. The fruiting phenophase also occurred throughout the year and showed an increase of species fruiting in June with a slight decrease in August and September. The data obtained in this study, when compared with other studies in different Atlantic Rainforest areas, indicates a seasonal pattern for the flowering phenophase and a variation in fruit availability throughout the year as well as in the fruiting peaks. Therefore, studies that observe flowering and fruiting events in loco are of main importance because they provide information on reproductive seasons of species for use in environmental restoration projects and thus alleviate the situation of degradation of riparian forests.


2019 ◽  
Author(s):  
Stephen P. De Lisle ◽  
Gonzalo Hernando ◽  
Daniel I. Bolnick

AbstractWithin-species variation is a salient feature of natural populations, of substantial importance for species interactions. However, the community consequences of sexual dimorphism, one of the most ubiquitous sources of within-species variance, remains poorly understood. Here, we extend classical models of consumer-resource dynamics to explore the ecological consequences of consumer sexual dimorphism. We show that sexual dimorphism in consumer attack rates on two different resource species promotes coexistence between those resources, mitigating the effects of both apparent competition and direct interspecific competition. Consumer sexual dimorphism can prevent exclusion of a resource with inferior growth rates because reduction in any of the two resources reduces consumer density, generating negative frequency dependence that stabilizes coexistence between resources. Our work highlights ecological sex differences as a potentially key factor governing the assembly of ecological communities, illustrating that the specific source of within-species variance can have important implications for community ecology.


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