Sexual Size Dimorphism and Reproductive Investment by Female Spiders: A Comparative Analysis

Prenter, John; Elwood, Robert W.; Montgomery, W. Ian

doi:10.2307/2640458

Cited by 118 publications

(92 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…First, while selection may favour small males in aerial competition due to higher maneuverability 56,57 , the more common contests on the ground typically select for larger males [57][58][59][60] . Second, female-biased SSD can arise through selection on female fecundity, possibly enhanced by male preference for large females 61,62 . Third, natural selection may favour different body sizes if dimorphic species can avoid resource competition or increase feeding efficiency by exploiting a wider range of resources compared with sexually monomorphic species [63][64][65] .…”

Section: Methodsmentioning

confidence: 99%

Female monopolization mediates the relationship between pre- and postcopulatory sexual traits

et al. 2014

View full text Add to dashboard Cite

Theory predicts a trade-off between investments in precopulatory (ornaments and armaments) and postcopulatory (testes and ejaculates) sexual traits due to the costs associated with their growth and maintenance within the finite energy resources available. Empirical studies, however, have revealed considerable inconsistency in the strength and direction of relationships among these sexual traits. Ambiguity may result from variance in the marginal benefits gained by increasing investments in either pre-or postcopulatory sexual traits. Here, in a broad comparative study, we test the prediction that the relationship between pre-and postcopulatory sexual traits differs among taxa relative to the importance of male-male contest competition within them. We find that covariance between pre-and postcopulatory sexual traits gradually shifts from strongly positive to strongly negative with increasing male-male contest competition. Thus, our findings reveal a potentially unifying explanation for the oftentimes inconsistent relationships in the strength and direction of covariance among sexual traits.

show abstract

Section: Methodsmentioning

confidence: 99%

Female monopolization mediates the relationship between pre- and postcopulatory sexual traits

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Although sexual size dimorphism is common in spiders (15)(16)(17), it is extreme in the cobweb spider, Tidarren (Araneae, Theridiidae) (18)(19)(20). In this genus, sexual size dimorphism results from a decrease in male size (19,21,22) and an increase in female size (20).…”

mentioning

confidence: 99%

Overcoming an evolutionary conflict: Removal of a reproductive organ greatly increases locomotor performance

Ramos

Irschick

Christenson

2004

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

One potential consequence of sexual size dimorphism is conflict among characters. For example, a structure evolved for reproduction can impair performance during other activities (e.g., locomotion). Here we provide quantitative evidence for an animal overcoming an evolutionary conflict generated by differential scaling and sexual size dimorphism by obligatorily removing an undamaged reproductive organ, and thus dramatically enhancing its locomotor performance. The spider genus Tidarren (Araneae, Theridiidae) is interesting because, within several species presenting extreme sexual size dimorphism (males representing Ϸ1% of the total mass of the female), males voluntarily remove one of their two disproportionately large pedipalps (modified copulatory organs; a single one represents Ϸ10% of the body mass in an adult) before achieving sexual maturity. Whether the left or right pedipalp is removed appears to be random. Previous researchers have hypothesized that pedipalp removal might enhance locomotor performance, a prediction that has remained untested. We found that, for male Tidarren sisyphoides, maximum speed increased (44%) significantly and endurance increased (63%) significantly after pedipalp removal. Furthermore, spiders with one pedipalp moved Ϸ300% greater distances before exhaustion and had a higher survival after exertion than those with two pedipalps. Removal of the pedipalp may have evolved in male Tidarren because of enhanced abilities to search for females (higher endurance and survival after exertion) and to out-compete rival males on the female's web (higher maximum speed). Our data also highlight how the evolution of conflicts can result in the evolution of a novel behavior.A central tenet of optimality theory is that natural selection will optimize structure and performance resulting in an overall highly fit organism (1, 2). Many studies, however, have shown that the evolution of high performance in one task can lead to decreased performance during another task (e.g., refs. 3-5). In extreme cases of such apparent conflicts, a structure evolved for one activity can substantially impair performance during another activity. For example, Darwin (6) described how sexual selection for sex differences might lead to such functional conflicts, particularly in males. He depicted how the relatively elaborate feathers in some male birds result in enhanced reproductive success via female mate choice, yet also reduces or constrains flight capacities, thus potentially making the animal more susceptible to predators (7). A relatively unexplored area is how organisms cope with these constraints imposed by factors such as sexual selection, natural selection, or allometry. One view of constraints is that they limit or hinder morphological or behavioral change, but another possibility is that constraints can result in a novel phenotype or behavior (8, 9). For example, as plethodontid salamanders undergo evolutionary miniaturization (become smaller), they shift from a terrestrial to an arboreal lifestyle (10). This ...

show abstract

“…En L. laeta el dimorfi smo sexual de las extremidades locomotoras fue claro, pero no extremo como en algunas arañas de telas orbitales de la familia Theridiidae los machos tienen el 1% de la masa de la hembra. Este resultado es consistente con lo reportado para otras arañas del suelo (Enders 1976;Prenter et al 1999;Gasnier et al 2002;Framenau 2005), pero menor que lo reportado para arañas tejedoras de telas (Hormiga et al 1995;.…”

Section: Discussionunclassified

“…Las arañas que viven a ras de suelo son menos dimórfi cas que las que construyen telas, lo que ha sido atribuido a sus diferentes estrategias reproductivas y de forrajeo (Enders 1976;Prenter et al 1997Prenter et al , 1998Prenter et al , 1999. A pesar de esto hay evidencias de dimorfi smo sexual en las estructuras locomotoras en estas arañas (e.g., Gasnier et al 2002;Framenau 2005).…”

Section: Introduccionunclassified

Dimorfismo sexual y morfología funcional de las extremidades de Loxosceles laeta (Nicolet, 1849)

et al. 2016

View full text Add to dashboard Cite

RESUMENLas relaciones alométricas entre rasgos morfológicos aportan evidencia de las fuerzas evolutivas que actúan sobre un rasgo particular. Las arañas que viven a ras de suelo son menos dimórfi cas que las que construyen telas, lo que ha sido atribuido a sus diferentes estrategias reproductivas y de forrajeo. Se ha propuesto que las largas extremidades en machos con respecto a la masa conducen a una optimización de los costos de locomoción. El objetivo de este estudio fué caracterizar la variabilidad de las dimensiones de las extremidades en la araña del rincón Loxosceles laeta y comparar las relaciones alométricas de las extremidades locomotoras entre ambos sexos. Tanto machos como hembras mostraron una alometría negativa de las extremidades, es decir las arañas con tamaño mayor tienen patas proporcionalmente más cortas que aquellas con cefalotórax más cortos, lo cual puede ser explicado por causas biomecánicas. Los machos presentaron patas más largas que las hembras tanto en tamaño absoluto como relativo. Esto sugiere que los machos tienen una mayor efi ciencia locomotora. El tamaño corporal pequeño está relacionado con bajo costo de transporte lo que asociado con patas largas es la morfología esperada para los machos más activos y móviles en esta especie. PALABRAS CLAVE:Loxosceles, Dimorfi smo sexual, Alometría, Extremidades. ABSTRACTAlometric relationships among morphological characters provide evidence of the evolutionary forces that act on a particular trait. Spiders that live on the ground are less dimorphic than orb web spiders, which have been attributed to their different reproductive and foraging strategies. It has been proposed that long legs with respecto to the body size in males, yields an optimization of locomotion costs. The aim of this study was to characterize the variability of the length of legs in the Chilean recluse spider Loxosceles laeta and to compare the alometric relationships of the locomotor legs in males and females. Both sexes showed negative alometric relationships between the length of the legs and the lengtgh of the cephalotorax, ie spiders of large body size have proportionally shorter legs than that of small body size, which may be explained by bio mechanic causes. The males showed longer legs than females both in absolute and relative terms. That means that males have a higher locomotor effi ciency than females. The relative small body size is related to a low transportation cost, which associated with long legs is the expected morphology for the more active and mobile males in this species. KEYWORDS:Loxosceles, Sexual dimorphism, Alometry, Legs. INTRODUCCIONLa anatomía funcional establece que el dimorfi smo sexual no solo se debe a diferencias en masas sino que también a diferencias en el tamaño relativo de las diferentes partes del cuerpo de un organismo (Thompson 1961). Las relaciones alométricas entre rasgos morfológicos aportan evidencia de las fuerzas evolutivas como selección sexual, que actúan sobre un rasgo particular (Anderson 1994;Stern & Emlen 1999;Emlen 2008).

show abstract

Sexual Size Dimorphism and Reproductive Investment by Female Spiders: A Comparative Analysis

Cited by 118 publications

References 0 publications

Female monopolization mediates the relationship between pre- and postcopulatory sexual traits

Female monopolization mediates the relationship between pre- and postcopulatory sexual traits

Overcoming an evolutionary conflict: Removal of a reproductive organ greatly increases locomotor performance

Dimorfismo sexual y morfología funcional de las extremidades de Loxosceles laeta (Nicolet, 1849)

Contact Info

Product

Resources

About