A morphometric comparison of three closely related species of Myrmica (Formicidae), including a new species from England
01 Apr 1978-Systematic Entomology (BioStor)-Vol. 3, Iss: 2, pp 131-145
TL;DR: This paper describes the form as a new parasitic species, Myrmica hirsuta sp.n.
Abstract: In the course of a population study on Myrmica sabuleti Meinert a miniature queen was found in some colonies. This paper describes the form as a new parasitic species, Myrmica hirsuta sp.n., and shows how an analogous male was identified. Twelve measurements were then made on a sample of males and females of this new species and these were compared with M. sabuleti and Myrmica scabrinodis Nyl. using a multivariate discriminating technique. The status of the new species is discussed.
TL;DR: Evolution of social organization can be important in generating intrinsic selective regimes that channel subsequent social evolution and in initiating the development of significant population genetic structure, including barriers to gene flow important in cladogenesis.
Abstract: Social organisms exhibit conspicuous intraspecific variation in all facets of their social organization. A prominent example of such variation in the highly eusocial Hymenoptera is differences in the number of reproductive queens per colony, Differences in queen number in ants are associated with differences in a host of reproductive and social traits, including queen phenotype and breeding strategy, mode of colony reproduction, and pattern of sex allocation. We examine the causes and consequences of changes in colony queen number and associated traits using the fire ant Solenopsis invicta as a principal model. Ecological constraints on mode of colony founding may act as important selective forces causing the evolution of queen number in this and many other ants, with social organization generally perpetuated across generations by means of the social environment molding appropriate queen phenotypes and reproductive strategies. Shifts in colony queen number have profound effects on genetic structure within nests and may also influence genetic structure at higher levels (aggregations of nests or local demes) because of the association of queen number with particular mating and dispersal habits. Divergence of breeding habits between populations with different social organizations has the potential to promote genetic differentiation between these social variants. Thus, evolution of social organization can be important in generating intrinsic selective regimes that channel subsequent social evolution and in initiating the development of significant population genetic structure, including barriers to gene flow important in cladogenesis.
01 Dec 1986-Trends in Ecology and Evolution
TL;DR: Slave raids of Amazon ants, the beheading of the host colony's queen by a parasitic Bothriomyrmex female, or the protracted throttling of the hosts' queen by an Epimyrma female which has penetrated a Leptothorax nest are observed.
Abstract: Slave raids of Amazon ants, the beheading of the host colony's queen by a parasitic Bothriomyrmex female, or the protracted throttling of the host queen by an Epimyrma female which has penetrated a Leptothorax nest, are among the most intriguing behaviors to be observed in social parasitic ants. The evolutionary origin of these behaviors, however, is quite obscure, and further work is needed to elucidate how parasitic life cycles could have arisen from the ordinary social organization of ants.
01 Jul 1991-Biological Journal of The Linnean Society
TL;DR: It is concluded that inquiline species strictly following Emery's rule could have evolved by the intraspecific route, and such species provide evidence for West-Eberhard's “alternative adaptation” hypothesis that between-species diversity frequently stems from diversity within species.
Abstract: Inquiline ant species are workerless social parasites whose queens reproduce in colonies of other species alongside the host queens. Inquilines arise either when one non-parasitic species evolves into an inquiline parasite of another non-parasitic species (the interspecific hypothesis), or by the speciation of intraspecific inquilines from their host stock (the intraspecific hypothesis): it is unlikely that inquilines evolve from other forms of social parasite. This paper reviews the evidence for and against the inter-and intraspecific hypotheses. All inquilines are close phylogenetic relatives of their host species (loose ‘Emery's rule’), and some are their host's closest relative (strict ‘Emery's rule’). A problem for the interspecific hypothesis is how to explain the strict Emery's rule, because phylogenetic constraints on host choice are probably quite weak. By contrast, the intraspecific hypothesis has difficulty accounting for the parasites' sympatric reproductive isolation. Facultative polygyny, in which queens may found colonies alone or by adoption into an existing multi-queen colony, should promote the evolution of small intraspecific inquilines. This is because small colony-founding queens should preferentially seek adoption, which provides the opportunity to produce a sexual-only brood. We suggest that microgynes, i.e. miniature queens found in some polygynous ants, represent such parasites. We review the evidence that inquiline species have evolved intraspecifically from microgynes in Myrmica ants. The coexistence within a species of a monogynous (singly-queened) and a polygynous form is probably a phenomenon usually unconnected with inquiline evolution. The reproductive isolation of intraspecific inquilines plausibly arises from divergent breeding behaviour associated with the parasites' small size. Such divergence could involve either a temporal separation in mating episodes, with small parasites maturing early, or a spatial separation, with small males being sexually-selected to mate near the nest with small queens seeking adoption, instead of in mating aggregations. We conclude that inquiline species strictly following Emery's rule could have evolved by the intraspecific route. If so, such species provide evidence for West-Eberhard's “alternative adaptation” hypothesis that between-species diversity frequently stems from diversity within species. They also represent likely cases of sympatric speciation. We suggest work on the parasites' phytogeny, genetics, behaviour and mating biology to test these conclusions further.
01 Dec 1995-Population Ecology
TL;DR: It appears that most deviations from “normal” colony propagation can be explained by a decreased success of dispersal and solitary founding by solitary queens in certain types of habitats.
Abstract: In contrast to what is generally believed, the reproductive strategies of ants are remarkably diverse and include such different phenomena, as wingless female and male sexuals, reproduction by mated workers, thelytokous parthenogenesis, and complete workerlessness. We review the various reproductive life histories and investigate them in the light of recent models on the evolution of dispersal strategies and multiple-queening. It appears that most deviations from “normal” colony propagation can be explained by a decreased success of dispersal and solitary founding by solitary queens in certain types of habitats. Consequently, alternative reproductive strategies are found especially in those species, in which environmental conditions or a highly specialized way of life are thought to make solitary founding costly. Among the key factors, which determine the success of reproductive strategies, appear to be spatial and temporal distribution of habitats and the availability of nest sites.
Alfred Buschinger1•Institutions (1)
TL;DR: All forms of interspecific true social parasitism (excluding xenobiosis) orginated from a common “preparasitic” stage, a subpopulation of reproductives in polygynous colonies and species, with diverging sexual behavior (near-nest mating vs. swarming) and caste ratios (production of more sexuals vs. workers).
Abstract: According to current hypotheses the main types of social parasitism among ants, namely slavery, temporary parasitism, and inquilinism, arose from such features as predation on other ants, or territorial behavior, both presumed precursors of slavemaking, and polygyny, a presumed precursor of temporary parasitism and inquilinism. The latter is believed also to represent a final instar in several evolutionary pathways leading from slavery, temporary parasitism, and xenobiosis to this permanently parasitic, workerless condition. Speciation, the origin of parasitic species from their usually closely related host species, is suggested to occur due to temporary geographic isolation and subsequent transition of one of the newly formed daughter species to parasitism in the nests of the other. Evidence is presented suggesting that the main types of social parasitism originated independently of each other. 15 ant genera are parasitized exclusively by inquilines, Eve other genera exclusively by temporary parasites. Only four groups of non-parasitic ant species (Formica, Tet-ramorium, Leptothorax subgenera Leptothorax and Myrafant) have parasites of several types each. Within these roups, however, there is little evidence of evolutionary transitions from one type to another. The few exceptions, mainly workerless species of the genera Epimyrma and Chalepoxenus, represent parasites which clearly derive from slave-making congeners, but differ from ordinary inquilines in that they eliminate the host colony queens like their actively dulotic ancestors. The new hypothesis suggests that all forms of interspecific true social parasitism (excluding xenobiosis) orginated from a common “preparasitic” stage, a subpopulation of reproductives in polygynous colonies and species, with diverging sexual behavior (near-nest mating vs. swarming) and caste ratios (production of more sexuals vs. workers). Arguments for sympatric speciation are compiled. Various features of the ancestral, and then host species (colony sizes, population density and structure, transition from polygyny to monoyny, etc.), and of the “preparasite” (production of few, or no workers, etc.) may shape the developing parasite to become a slave-maker, inquiline, or temporary parasite. These features usually leave open only one, or in a few genera, several options. The different types of parasitism within one host species group thus may have developed in a radiative manner from the common, preparasitic stage, which explains that independent colony foundation is a common feature of all true social parasites among ants.
01 Oct 1973-Journal of Animal Ecology
17 Mar 1955-Evolution
Abstract: macrogyna: females and males larger, the largest sexual females with the head dark brown above and orange-brown below the eyes, with longer, more tapering ovarioles, of which the terminal filaments account for only onethird the total length in virgins, eyes less prominent but of the same size, colonies usually monogynous with relatively large aggressive workers, the average worker head-width less than the average female head-width, colony reproduction by dissemination of fertile females which found colonies either alone or in small aggregates; microgynca: females and males smaller, the smallest sexual females with head brown above and yellow-brown below the eyes, with shorter, less tapering ovarioles of which the terminal filaments account for two-fifths of the total length in virgins, eyes more prominent but of the same size, colonies polygynous with relatively small and docile workers, the average worker head-width similar to the average female headwidth, fertile females return to their nest (and possibly other nests) and colonies reproduce by fission.
01 Mar 1976-Insectes Sociaux
TL;DR: Data on the natural occurrence of the microgyne form of Myrmica rubra L. are given, showing it to be more common than previously suspected and it is concluded that microgynes perhaps being an atavistic form of the species.
Abstract: 1. Data on the natural occurrence of the microgyne form ofMyrmica rubra L. are given, showing it to be more common than previously suspected. 2. Morphometrics show that the microgynes are an isometric reduction of the normal queens. 3. Experimental evidence is given to show that microgynes tend to breed true and that they have a queen effect that is similar to normal queens. 4. The origin of the microgyne polymorphism is discussed and it is concluded that it is genetic, microgynes perhaps being an atavistic form of the species.
01 Jun 1974-Insectes Sociaux
TL;DR: The results imply that perhaps M. rubra and M. sabuleti do not have the same «queen effect» on larvae as do queens ofM.
Abstract: The populations and mean individual weight of queens and workers have been obtained from a sample of colonies for three species ofMyrmica; beingMyrmica rubra L.,Myrmica sabuleti Meinert andMyrmica scabrinodis Nylander. It was found thatM. scabrinodis have fewer and smaller workers than the other two species but the most important differences are in the queen populations.M. rubra average 15 queens per colony,M. sabuleti 3 andM. scabrinodis 2 while some colonies of bothM. rubra andM. sabuleti contain microgynes. There are usually some normal queens in microgynes colonies, slightly fewer than in normal colonies, but there are many more queens altogether. Microgyne colonies ofM. rubra average 60 queens and those ofM. sabuleti 20 queens.M. sabuleti normal queens weigh 6.3 mg, microgynes 3.8 mg,M. rubra normals 5.6 mg, microgynes 2.7 mg andM. scabrinodis 4.7 mg. Queen numbers have a negative influence on the mean individual weights of queens and workers in a colony whilst worker number has a positive influence. An important inplication of this observation is thatMyrmica colonies must tend to recruit daughters, rather than strangers, to add to and replace the foundress queens. This seems to be so even inM. scabrinodis that often has only one queen in a colony. It is suggested that these size relationships can be explained by the «queen effect», that has been well investigated in the laboratory. It is proposed that the greater the queen density (queens/worker) the greater the probability of an individual worker being under the influence of a queen and carrying out «queen effect» on the larvae, although this relationship is not linear. The results imply that perhapsM. sabuleti queens and microgynes of bothM. sabuleti andM. rubra do not have the same «queen effect» on larvae as do queens ofM. rubra andM. scabrinodis. Finally a diagram of the probable interactions between size and population of individuals in aMyrmica colony is presented and discussed.
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