Density-dependent impacts of invasive Vincetoxicum rossicum (pale swallowwort) and native Asclepias syriaca (common milkweed) on plant traits and competitive interactions

Coexistence of annual herbs Polygonum punctatum, a native, and Polygonum caespitosum, an immigrant, may result from (i) niche differentiation that reduces or avoids competition, (ii) competitive equivalence for shared resources, or (iii) interaction between a strong competitor and a species that tolerates competition. We investigated competitive interactions between the Polygonum congeners in a greenhouse experiment using plants grown from seed to seed set. Thinning profiles of monocultures were density dependent but did not differ between the species in monocultures. Biomass allocation to root, shoot, and racemes was not influenced by competition from conspecifics or congeners. Mature plant height and raceme production of both species were negatively affected by congener density; however, the species were not competitively equivalent. Polygonum caespitosum was suppressed into the shorter heights in mixture pots but produced more racemes at all but the greatest congener densities. Key words: competition, coexistence, annual herbs, immigrant.

Download Full-text

Population Dynamics and Stability

Ecology of Climate Change ◽

10.23943/princeton/9780691148472.003.0004 ◽

2013 ◽

Author(s):

Eric Post

Keyword(s):

Climate Change ◽

Population Dynamics ◽

Density Dependence ◽

Environmental Variation ◽

External Factors ◽

Competitive Interactions ◽

Density Dependent ◽

Survival And Reproduction ◽

Dependent Processes

This chapter examines the implications of climate change for population dynamics and stability. Population dynamics, or the variation in abundance of a population through time, can be decomposed into two components: density-dependent and density-independent processes. Density-dependent processes are those involving competitive interactions among members of the same species within the same population that influence survival and reproduction. Density-independent processes are those that do not involve interactions with other members of the same species in the same population but rather owe to external factors such as environmental variation. It is this latter set of processes that has relevance to climate change, though density dependence certainly has a role to play in the response of populations to climate change.

Download Full-text

A comparison of the host preference of monarch butterflies (Danaus plexippus ) for milkweed (Asclepias syriaca ) over dog-strangler vine (Vincetoxicum rossicum )

Entomologia Experimentalis et Applicata ◽

10.1046/j.1570-7458.2003.00049.x ◽

2003 ◽

Vol 107 (3) ◽

pp. 193-199 ◽

Cited By ~ 31

Author(s):

Heather R. Mattila ◽

Gard W. Otis

Keyword(s):

Host Preference ◽

Danaus Plexippus ◽

Asclepias Syriaca ◽

Monarch Butterflies ◽

Vincetoxicum Rossicum

Download Full-text

Effects of density dependent larval competition on the life history traits of Aedes aegypti and Aedes albopictus (Diptera: Culicidae)

Fragmenta Entomologica ◽

10.4081/fe.2017.238 ◽

2017 ◽

Vol 49 (1) ◽

pp. 97 ◽

Cited By ~ 1

Author(s):

Sampa Banerjee ◽

Soujita Pramanik ◽

Soumyajit Banerjee ◽

Goutam K. Saha ◽

Gautam Aditya

Keyword(s):

Life History ◽

Aedes Aegypti ◽

Life History Traits ◽

Population Level ◽

Competitive Interactions ◽

Pupal Weight ◽

Larval Competition ◽

Density Dependent ◽

Geographical Regions ◽

F2 Generation

Consequences of larval competition at the population level provide explanation for the differences in relative abundance of Aedes aegypti and Aedes albopictus in different geographical regions. The outcome of competition is assessed through the estimates of the life history traits as a response to varying density and resource available for larval development. In the present study, variations in the life history traits due to density-dependent intra- and inter- specific competition involving A. aegypti and A. albopictus were assessed following the minimalist model. The instar-I larvae (0-day old F2 generation) of both Aedes species were reared to the adult stages using the initial rearing density of 1, 2, 4 and 6 (individuals/10ml) in multiple replicates. The age at pupation, pupal weight, adult weight and adult wing length of the individuals were considered as the response variables and surrogates of estimating the competitive interactions. Density dependent variations in the competitive interactions were evident for both the mosquitoes with reference to the selected life history traits. In A. aegypti, the life history traits varied with the levels of competition, which was not observed for A. albopictus. Although the density levels considered in the present instance were lower than in earlier studies, the observations were similar, with A. albopictus being competitively superior. It appears that irrespective of the density levels, interspecific competition affects A. aegypti and thus may bear population level consequences and overall abundance in the areas where both species are present.

Download Full-text