Uniparental Species Research Articles

Lesser Prairie-chicken incubation behavior and nest success most influenced by nest vegetation structure.

Incubation breaks are necessary for any nesting bird but can increase the mortality risk of the nest or attending parent. How intrinsic and extrinsic variables affect nest attentiveness-the proportion of time a female is on nest during incubation- and subsequent survival of the nest remains unclear for uniparental species. We related female nest attentiveness to nest survival and tested the effects of intrinsic and extrinsic variables on nest attentiveness by female Lesser Prairie-chickens (Tympanuchus pallidicinctus) using GPS locations of 87 females at 109 nest sites in 3 study areas in Kansas during 2013-2015. Daily nest survival increased by 39% when nest attentiveness increased from 21% to 98%. Female Lesser Prairie-chickens were 18% less attentive as body mass increased from 600 to 920 g. Daily precipitation and temperature, controlled for days into the incubation period, had interactive effects on nest attentiveness with nest attentiveness lowest on cool, wet days and increasing as temperature increased, regardless of precipitation (41% attentiveness at 16°C and 79 mm of precipitation to 90% attentiveness at 37°C and 41 mm of precipitation). Nest attentiveness increased by 11% as the quantity of grass at the nest site increased from 5% to 78% when visual obstruction was at 1 and 2 decimeters (dm) and increased 9% as the quantity of grass at the nest site increased from 5% to 83% when visual obstruction was at its maximum (3 dm). Our findings reveal the critical importance of nest attentiveness and incubation behavior, not only in relation to demography, but within the context of changing environmental conditions. As warmer temperatures and extreme precipitation events become more common and change the growth rates of vegetation, species like the Lesser Prairie-chicken that are ground-nesting, rely on vegetation cover, and exhibit uniparental care could experience negative demographic consequences.

Interspecific differences in brood desertion by female diving ducks in relation to duckling age and environmental conditions

Studies on brood desertion in birds have been mainly conducted on species with biparental care, and less often on uniparental species. Females of many duck species remain with their ducklings, unassisted by males, during variable periods of time before the chicks can fledge. In this paper, we examined factors that influence brood desertion by female red-crested pochards ( Netta rufina), common pochards ( Aythya ferina) and white-headed ducks ( Oxyura leucocephala) during a 10-year period in lakes in southern Spain that experienced interannual variations in water levels. At an interspecific level, we found that brood desertion was less frequent in the species that nested earlier (red-crested pochard), while it was more frequent in the species that nested later (white-headed duck). Larger (older) ducklings were deserted more frequently than smaller ones in the three species. However, an interaction between flooding conditions in wetlands and species identity on brood desertion, after accounting for chick age, suggests that there were variations between the ducklings of the three species in their requirements for maternal care, conditioned by environmental conditions. Therefore, our study indicates that environmental conditions may affect parental care. A longer duration of brood attendance by female ducks may buffer against adverse effects of environmental conditions.

Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity

Most birds incubate their eggs, which requires time and energy at the expense of other activities. Birds generally have two incubation strategies: biparental where both mates cooperate in incubating eggs, and uniparental where a single parent incubates. In harsh and unpredictable environments, incubation is challenging due to high energetic demands and variable resource availability.We studied the relationships between the incubation behaviour of sandpipers (genus Calidris) and two environmental variables: temperature and a proxy of primary productivity (i.e. NDVI). We investigated how these relationships vary between incubation strategies and across species among strategies. We also studied how the relationship between current temperature and incubation behaviour varies with previous day's temperature.We monitored the incubation behaviour of nine sandpiper species using thermologgers at 15 arctic sites between 2016 and 2019. We also used thermologgers to record the ground surface temperature at conspecific nest sites and extracted NDVI values from a remote sensing product.We found no relationship between either environmental variables and biparental incubation behaviour. Conversely, as ground-surface temperature increased, uniparental species decreased total duration of recesses (TDR) and mean duration of recesses (MDR), but increased number of recesses (NR). Moreover, small species showed stronger relationships with ground-surface temperature than large species. When all uniparental species were combined, an increase in NDVI was correlated with higher mean duration, total duration and number of recesses, but relationships varied widely across species. Finally, some uniparental species showed a lag effect with a higher nest attentiveness after a warm day while more recesses occurred after a cold day than was predicted based on current temperatures.We demonstrate the complex interplay between shorebird incubation strategies, incubation behaviour, and environmental conditions. Understanding how species respond to changes in their environment during incubation helps predict their future reproductive success.

Effect of Temperature on the Survival and Developmental Rate of Immature Ooencyrtus mirus (Hymenoptera: Encyrtidae).

Bagrada hilaris (Burmeister) is an invasive pest of cole crops in the southwestern United States. To find potential biocontrol agents of B. hilaris, three egg parasitoids were imported from Pakistan, including Ooencyrtus mirus, a recently described uniparental species. We investigated the effect of temperature on survival and developmental rate in O. mirus from egg to adult. At 14 and 16°C, no adults emerged unless the immatures were transferred later to a warmer temperature. At constant 18°C, a low percentage emerged, but again more emerged if the immatures were transferred to a warmer temperature. Survival ranged from 80 to 96% at 20-37°C and did not differ significantly among these temperatures. No adults emerged at 38°C. Regardless of the amount of time the parasitized eggs were held at 14 and 16°C, the developmental times after returning the eggs to 26°C were similar, suggesting a quiescence process rather than simply slow development. At higher temperatures, the developmental rate increased linearly from 18 to 36°C and then declined at 37°C. The Wang model provided the best fit of the data and estimated a lower developmental threshold at 13.0°C, an optimal temperature at 35.6°C, and an upper developmental threshold of 38.3°C. The thermal constant for total immature development is 168.4 degree-days. The results show 36°C to be the best temperature for rearing O. mirus, and that O. mirus-parasitized eggs can be stored at 14°C for months without losing viability. These are crucial data to consider when mass rearing this biological control agent.

Hormonal and neural correlates of care in active versus observing poison frog parents

The occasional reversal of sex-typical behavior suggests that many of the neural circuits underlying behavior are conserved between males and females and can be activated in response to the appropriate social condition or stimulus. Most poison frog species (Family Dendrobatidae) exhibit male uniparental care, but flexible compensation has been observed in some species, where females will take over parental care duties when males disappear. We investigated hormonal and neural correlates of sex-typical and sex-reversed parental care in a typically male uniparental species, the Dyeing Poison Frog (Dendrobates tinctorius). We first characterized hormone levels and whole brain gene expression across parental care stages during sex-typical care. Surprisingly, hormonal changes and brain gene expression differences associated with active parental behavior in males were mirrored in their non-caregiving female partners. To further explore the disconnect between neuroendocrine patterns and behavior, we characterized hormone levels and neural activity patterns in females performing sex-reversed parental care. In contrast to hormone and gene expression patterns, we found that patterns of neural activity were linked to the active performance of parental behavior, with sex-reversed tadpole transporting females exhibiting neural activity patterns more similar to those of transporting males than non-caregiving females. We suggest that parallels in hormones and brain gene expression in active and observing parents are related to females' ability to flexibly take over parental care in the absence of their male partners.

How should we treat autopolyploid and parthenogenetic animals taxonomically?

Asexually reproducing and polyploid animals are unresolved problems of taxonomy and nomenclature. The present paper discusses this issue from a theoretical perspective and outlines how the problem was treated in the past. The autotriploid, obligately parthenogenetic marbled crayfish is used as an example to elaborate the conditions under which autopolyploids and parthenogens should be described as separate uniparental species.

Temporary Mate Removal During Incubation Leads to Variable Compensation in a Biparental Shorebird

Theoretical models predict that parents feeding offspring should partially compensate for the reduced care of their partner. However, for incubating birds, the level of compensation may depend on how reduced care changes the risk of entire brood failure, for example due to clutch predation, and on individual variation in the timing of depletion of energy stores. Although biparental incubation dominates in non-passerines, short-term manipulations of care during incubation are scarce. Here, we describe the response of 25 semipalmated sandpipers (Calidris pusilla) to an unexpected ~12-hour absence (experimental removal) of their partner in the middle of the 21-day incubation period. During the period when the removed partner would have taken over to start its regular ~12-hour incubation bout, parents compensated partially for the absence of their partner’s care (mean: 59%). However, individuals varied in their response from no to full compensation, independent of parental sex. In contrast to incubation in undisturbed nests or by uniparental species, nest attendance of compensating parents tended to be higher during the warmer part of the day. Whereas compensation was unrelated to before-experimental share of incubation, parents that left the nest from a further distance upon human approach (more aware of or more ‘responsive’ to their environment) compensated more. The quality of incubation in the after-experimental period, i.e. after return of the partner, was lower than usual, but improved quickly over time. In seven nests where the removed parent never returned, the widowed partner attended the nest for 0-10 days (median: 4), which suggests that widowed semipalmated sandpipers can adjust their incubation behavior to that observed in uniparental incubators. To conclude, our results indicate that biparental incubators are willing to tolerate a missed or irregular incubation bout of their partner and we speculate that all individuals would compensate fully, but that some fail because they deplete their energy stores, while others may be less responsive to or initially even unaware of the absence of their partner.

Biological traits of Quadrastichus mendeli (Hymenoptera, Eulophidae), parasitoid of the eucalyptus gall wasp Leptocybe invasa (Hymenoptera, Eulophidae) in Thailand.

Quadrastichus mendeli Kim & La Salle, a parasitoid of Leptocybe invasa Fisher & La Salle, is a uniparental species. This study assessed the biological traits of Q. mendeli in the laboratory at a temperature of 27 ± 1 °C. Diets had a highly significant effect on the mean longevity of female Q. mendeli. Feeding honey solution prolonged the mean longevity of the parasitoid to 4.80 days. The estimated 50% survival period was 3 days. The mean potential fecundity in all ages was 8.85 eggs per female. Age had a highly significant effect on the mean egg load. There was a positive relationship between egg load and female size. The mean of realized fecundity throughout the life span was 2.47 progenies per female. The mean developmental time of Q. mendeli from the egg to adult stage was 27.06 days. The shorter developmental time of Q. mendeli in comparison to its host can be considered a reason for the successful control of L. invasa in Thailand.

Parental investment of male Peregrine Falcons during incubation: influence of experience and weather

Incubation involves a transfer of heat between parent and embryo. The brood patch is pressed against one surface of the egg, and warming occurs as a result of adjustments in both blood flow through the brood patch and heat production by the parent. A brood patch normally develops in both sexes in bird species where incubation is biparental. But in uniparental species, where the male does not incubate, or in species where he contributes to incubation for short periods only (e.g. Peregrine Falcon), the brood patch is absent or poorly developed in males. Considering that male peregrines do not develop a brood patch, and by consequence have less efficient heat transmission capabilities, we tested four hypotheses related to the time devoted to incubation by male peregrines. This study was conducted on a long-term-monitored population located in northern Spain. We spent 482.73 h monitoring peregrine incubation events in 37 territories from 2008 to 2016. We observed 203 changeovers. Males relieved females 3.02 ± 2.61 times per day. The changeover rate was not regularly distributed throughout the daylight period. Males devoted 114.3 ± 84.24 min to each incubation event. The time invested by males in incubation was strongly related to their level of experience at breeding in the territory. However, there were no significant relationships between the time devoted by males to incubation and their previous accumulated reproductive success. Neither was there a relationship between reproductive performance and the time invested by males in incubation. The time that males devoted to incubation was significantly related to the environmental temperature. It seemed that males devoted nonsignificantly slightly less time to incubation during the first and last weeks of the incubation process. This results demonstrate that the uniparental scheduling in Peregrine Falcons is conditioned firstly by ambient factors and secondly by male experience.

The First Parthenogenetic Pleurodont Iguanian: A New All-femaleLiolaemus(Squamata: Liolaemidae) from Western Argentina

Vertebrate taxa with entirely unisexual populations are composed of females that reproduce without fertilization and are generally of hybrid origin. At least 23 vertebrate families have unisexual lineages. Within squamate reptiles, >40 uniparental species have been described from five major lineages: acrodont iguanians, Gekkota, Serpentes, Scincomorpha, and Varanidae. Pleurodont iguanians include >1100 species, all of which have gonochoristic reproduction. Here we report the discovery of a new unisexual lizard from the liolaemid genus Liolaemus, a species-rich (∼260 species) clade distributed over most of southern South American. The new species, Liolaemus parthenos, is the only known all-female triploid pleurodont iguanian. The structural chromosome heteromorphisms of the karyotypes support the hypothesis that L. parthenos is the product of a hybrid origin. Based on morphology, the new species is assignable to the L. boulengeri group (sensu Abdala, 2007), and phylogenetic analyses of mitochondrial DNA in...

Mothers teach daughters because daughters teach granddaughters: the evolution of sex-biased transmission

Cultural transmission in nonhuman animals is often sex biased, with females more frequently or efficiently learning cultural behaviors than males. The evolutionary origins of sex-biased cultural transmission have been a mystery, though it has been proposed that female offspring may gain greater reproductive benefit from cultural traits than sons—the hypothesis. I propose a different, hypothesis where sex-biased transmission evolves in uniparental species if mothers teach, that is, invest in their offsprings’ learning. I show, with theoretical models, that mothers evolve to invest more in teaching daughters than sons because teaching daughters results in greater inclusive fitness benefits. Teaching a son gives him a reproductive benefit for one generation. However, I show that because daughters may teach future generations, teaching a daughter can be a better long-term investment. I also model the disparate benefits hypothesis and show that the uniparental teaching hypothesis better fits the empirical patterns of sex-biased transmission in the well-studied example of sponging in bottlenose dolphins. Uniparental teaching may also explain sex-biased transmission in other species, including chimpanzees. My findings suggest that controversial mechanisms of cultural transmission in nonhumans, such as teaching, may be inferred from population-level patterns of transmission even when it is difficult to observe transmission directly in the field or laboratory.

The effects of heterospecifics and climatic conditions on incubation behavior within a mixed‐species colony

Parental incubation behavior largely influences nest survival, a critical demographic process in avian population dynamics, and behaviors vary across species with different life history breeding strategies. Although research has identified nest survival advantages of mixing colonies, behavioral mechanisms that might explain these effects is largely lacking. We examined parental incubation behavior using video‐monitoring techniques on Alcatraz Island, California, of black‐crowned night‐heron Nycticorax nycticorax (hereinafter, night‐heron) in a mixed‐species colony with California gulls Larus californicus and western gulls L. occidentalis. We first quantified general nesting behaviors (i.e. incubation constancy, and nest attendance), and a suite of specific nesting behaviors (i.e. inactivity, vigilance, preening, and nest maintenance) with respect to six different daily time periods. We employed linear mixed effects models to investigate environmental and temporal factors as sources of variation in incubation constancy and nest attendance using 211 nest days across three nesting seasons (2010–2012). We found incubation constancy (percent of time on the eggs) and nest attendance (percent of time at the nest) were lower for nests that were located < 3 m from one or more gull nest, which indirectly supports the predator protection hypothesis, whereby heterospecifics provide protection allowing more time for foraging and other self‐maintenance activities. To our knowledge, this is the first empirical evidence of the influence of one nesting species on the incubation behavior of another. We also identified distinct differences between incubation constancy and nest attentiveness, indicating that these biparental incubating species do not share similar energetic constraints as those that are observed for uniparental species. Additionally, we found that variation in incubation behavior was a function of temperature and precipitation, where the strength of these effects was dependent on the time of day. Overall, these findings strengthen our understanding of incubation behavior and nest ecology of a colonial‐nesting species.

Fathering in rodents: Neurobiological substrates and consequences for offspring

This article is part of a Special Issue “Parental Care”. Paternal care, though rare among mammals, is routinely displayed by several species of rodents. Here we review the neuroanatomical and hormonal bases of paternal behavior, as well as the behavioral and neuroendocrine consequences of paternal behavior for offspring. Fathering behavior is subserved by many of the same neural substrates which are also involved in maternal behavior (for example, the medial preoptic area of the hypothalamus). While gonadal hormones such as testosterone, estrogen, and progesterone, as well as hypothalamic neuropeptides such as oxytocin and vasopressin, and the pituitary hormone prolactin, are implicated in the activation of paternal behavior, there are significant gaps in our knowledge of their actions, as well as pronounced differences between species. Removal of the father in biparental species has long-lasting effects on behavior, as well as on these same neuroendocrine systems, in offspring. Finally, individual differences in paternal behavior can have similarly long-lasting, if more subtle, effects on offspring behavior. Future studies should examine similar outcome measures in multiple species, including both biparental species and closely related uniparental species. Careful phylogenetic analyses of the neuroendocrine systems presumably important to male parenting, as well as their patterns of gene expression, will also be important in establishing the next generation of hypotheses regarding the regulation of male parenting behavior.

Flexible compensation of uniparental care: female poison frogs take over when males disappear.

Parental care systems are shaped by costs and benefits to each sex of investing into current versus future progeny. Flexible compensatory parental care is mainly known in biparental species, particularly where parental desertion or reduction of care by 1 parent is common. The other parent can then compensate this loss by either switching parental roles and/or by increasing its own parental effort. In uniparental species, desertion of the caregiver usually leads to total brood loss. In the poison frog, Allobates femoralis, obligatory tadpole transport (TT) is generally performed by males, whereas females abandon their clutches after oviposition. Nevertheless, in a natural population we previously observed 7.8% of TT performed by females, which we could link to the absence of the respective fathers. In the following experiment, under laboratory conditions, all tested A. femoralis females flexibly took over parental duties, but only when their mates were removed. Our findings provide clear evidence for compensatory flexibility in a species with unisexual parental care. Contrary to the view of amphibian parental care as being stereotypical and fixed, these results demonstrate behavioral flexibility as an adaptive response to environmental and social uncertainty. Behavioral flexibility might actually represent a crucial step in the evolutionary transition from uniparental to biparental care in poison frogs. We suspect that across animal species flexible parental roles are much more common than previously thought and suggest the idea of a 3-dimensional continuum regarding flexibility, parental involvement, and timing, when thinking about the evolution of parental care.

Do Female Penduline TitsRemiz pendulinusAdjust Parental Decisions to Their Mates' Behaviour?

Czyz B. 2011. Do female Penduline Tits Remiz pendulinus adjust parental decisions to their mates' behaviour? Ardea 99: 27–32.In contrast to older models of parental care, recent theoretical models assume that parents do not make their decisions independently of one another, but respond to the behaviour of their mates. Studies involving mate removal have mostly been conducted in biparental species and such experiments in uniparental species are scarce. I studied the Penduline Tit Remiz pendulinus, a small passerine bird with uniparental care provided either by a female (45% in the studied population) or a male (17%). During the egg-laying period, one parent (or both; 38% in the studied population) deserts the clutch and starts a new breeding attempt. The aim of this study was to find out whether the parental care decision of female Penduline Tits is affected by their mate's decision to desert or not. In the control group (nests where males were caught, ringed and released), almost 50% of the females deserted the nest. By contrast, most females from the manipulated group did not desert their nests after I had removed their mates. In the following days 12 experimental females (60%) mated with replacement males at their nests; this behaviour was not observed in the control group, and is very rare in the study population (3.7%). These results may suggest that female behaviour is affected by the male decision to desert or stay. However, after attracting a replacement male, some females deserted their nests. As a result, only 11 experimental females (55%) stayed and started incubation, which represents a proportion similar to that found in the control group. This study shows that Penduline Tit females respond in real time to the behaviour of their mates and that their reproductive tactics are flexible.

Intraseasonal patterns in shorebird nest survival are related to nest age and defence behaviour

Nest survival may vary throughout the breeding season for many bird species, and the nature of this temporal variation can reveal the links between birds, their predators, and other components of the ecosystem. We used program Mark to model patterns in nest survival within the breeding season for shorebirds nesting on arctic tundra. From 2000 to 2007, we monitored 521 nests of five shorebird species and found strong evidence for variation in nest survival within a nesting season. Daily nest survival was lowest in the mid-season in 5 of 8 years, but the timing and magnitude of the lows varied. We found no evidence that this quadratic time effect was driven by seasonal changes in weather or the abundance of predators. Contrary to our prediction, the risk of predation was not greatest when the number of active shorebird nests was highest. Although nest abundance reached a maximum near the middle of the breeding season, a daily index of shorebird nest activity was not supported as a predictor of nest survival in the models. Predators' access to other diet items, in addition to shorebird nests, may instead determine the temporal patterns of nest predation. Nest survival also displayed a positive, linear relationship with nest age; however, this effect was most pronounced among species with biparental incubation. Among biparental species, parents defended older nests with greater intensity. We did not detect a similar relationship among uniparental species, and conclude that the stronger relationship between nest age and both nest defence and nest survival for biparental species reflects that their nest defence is more effective.

Uniparental inheritance of organelle genes

Uniparental inheritance of organelle genes

Biological control of the eucalyptus gall wasp Ophelimus maskelli (Ashmead): Taxonomy and biology of the parasitoid species Closterocerus chamaeleon (Girault), with information on its establishment in Israel

Closterocerus chamaeleon (Girault) (Hymenoptera; Eulophidae) was introduced into Israel for biological control of its family member, a gall-inducing pest Ophelimus maskelli (Ashmead). Closterocerus chamaeleon appears to be a widespread species in Australia, ranging from northern Queensland to Victoria and Western Australia. It was reared from galls on Eucalyptus camaldulensis Dehnh., E. tereticornis (=umbellata Smith.), E. amplifolia Naudin, E. cloziana F.Muell. and E. rudis Endl. Closterocerus chamaeleon is a uniparental species; at 25 °C the entire development was completed in 3 weeks. Galls containing late second or third instar larvae and pupae of O. maskelli are suitable for successful development. A total of about 12,000 C. chamaeleon adults were liberated in Israel. Our findings suggest that C. chamaeleon seems to be an efficient agent and has already lowered the population density of its host galler in some locations after less than a year since its release. The parasitoid is active throughout the winter when development of its host is virtually arrested. The fast spread of C. chamaeleon was demonstrated by its occupying areas 120 km away from the release point in less than a year. Green sticky traps are a reliable and practical device for monitoring and sampling both O. maskelli and C. chamaeleon. The taxonomy of C. chamaeleon is discussed, as well as several aspects of its life seasonal histories, effect of food on adult survival and its role in possible successful control of O. maskelli.

Time allocation between feeding and incubation in uniparental arctic‐breeding shorebirds: energy reserves provide leeway in a tight schedule

Birds with uniparental incubation may face a time allocation problem between incubation and feeding. Eggs need regular warming to hatch successfully, but the parent must leave the nest to feed and safeguard its own survival. Time allocation during incubation is likely to depend on factors influencing egg cooling rates, parental energy requirements and feeding intake rate. How this allocation problem is resolved was subject of this study on arctic‐breeding shorebirds. We compared incubation rhythms between four uniparental shorebird species differing in size and expected to find both species differences and weather effects on the organisation of incubation.Attentive behaviour and responses to variation in weather showed a remarkable consistency across species. All species alternated feeding bouts (recesses) with brooding bouts throughout the day. Recesses were concentrated in the warmer parts of the day, while recess duration showed little diurnal variation. Despite continuous daylight, a pronounced day‐night rhythmicity was apparent. The four species in this study spent a similar proportion (13–19%) of the time off their nest. After correction for weather effects, the number of recesses was largest in the smallest species, while recess duration was longest in the largest species. Total recess time per day increased on cold days through an increase of mean recess length, while the number of recesses decreased.Comparing our observations to predictions derived from criteria that birds might use to organise their attentive behaviour, showed that the limits are set by parental requirements, while the energy stores of adults provide some leeway for short‐term adjustments to environmental variability.If breeding birds trade off feeding time against incubation time, energy stores are expected to be influenced by weather. We expected uniparental species to be more likely to show weather effects on condition than biparentals, as in the latter ‘off duty’ time is much larger and independent of weather. This prediction was tested by comparing energy stores in two uniparental species and a biparental congener. While body mass of uniparental incubators decreased after a period with low temperatures, body mass of the biparental species did not.

Female nest defense in a coral-reef fish, Dascyllus albisella , with uniparental male care

Intraspecific variation in the patterns of parental care has been observed in a variety of animals; however, the possibility of parental care by a non-caregiving parent of uniparental species has not been thoroughly explored. In the coral-reef damselfish, Dascyllus albisella, only males normally exhibit parental care. In this study, we examined the response of females of this species to egg predators after experimental male removal and an elevated level of egg predation, at two small patch reefs (reefs 1 and 2) in Hawaii. We tested theoretical expectations that a nest was defended only by females which had spawned in the nest, and that larger females had a higher likelihood of defense than smaller females. A nest was defended against egg predators more frequently by females that had spawned in that nest than would be expected by chance. Not all females that had spawned in a given nest participated in defense. There was a positive association between female body length and the likelihood of defense at reef 2, but not at reef 1. Within a set of females that had spawned in the same nest during the same nesting cycle, defending females had larger body lengths than non-defending females at reef 2 but not at reef 1. Lack of association between female size and likelihood of defense at reef 1 was unexpected, but may correlate with the smaller average female size and smaller size differences among females on that reef.