scholarly journals Equality between the sexes in plants for costs of reproduction; evidence from the dioecious Cape genus Leucadendron (Proteaceae)

2017 ◽  
Author(s):  
Jeremy J. Midgley ◽  
Adam G. West ◽  
Michael D. Cramer
Keyword(s):  
Life History ◽  
Fire Ecology ◽  
Sex Ratios ◽  
Costs Of Reproduction ◽  
Male And Female ◽  
Reproductive Synchrony ◽  
Male Function ◽  
Female Function ◽  
Mating Opportunities ◽  
Dimorphic Species

AbstractIt has been argued that sexual allocation is greater for female function than male function in plants in general and specifically for the large dioecious Cape genus Leucadendron. Here, we use new interpretations of published information to support the hypothesis of equality between sexes in this genus. The explanations are based on the fire ecology of the Cape that results in reproductive synchrony, reproductive doubling and competitive symmetry. Firstly, strict post-fire seedling establishment of the reseeder life-history in the Cape results in single-aged populations. Consequently, the reproductive and vegetative schedules of males must synchronously track that of females. This implies equal allocation to sex. Secondly, after fires, dioecious females have double the seedling to adult ratio of co-occurring hermaphrodites. This indicates that being liberated from male function allows females access to resources that double their fitness compared to hermaphrodites. Therefore, male and female costs of reproduction are equal in hermaphrodites. Thirdly, competitive symmetry must occur because males and female plants will frequently encounter each other as close near neighbours. Competitive asymmetry would both reduce mating opportunities and skew local sex ratios. The evidence to date is for 1:1 sex ratios in small plots and this indicates competitive symmetry and a lack of dimorphic niches. Finally, vegetatively dimorphic species must also allocate equally to sex, or else sexual asynchrony, lack of reproductive doubling or competitive asymmetry will occur.

Female and male costs of reproduction must be equal in dioecious Cape plant genus Leucadendron (Proteaceae)

2019 ◽  
Vol 67 (7) ◽  
pp. 517
Author(s):  
Jeremy J. Midgley ◽  
Adam G. West ◽  
Michael D. Cramer
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Output ◽  
Sex Ratios ◽  
Reproductive Allocation ◽  
Costs Of Reproduction ◽  
Male And Female

The Cape Leucadendron genus is dioecious, with extreme vegetative dimorphism displayed in some species – females having much larger leaves and fewer branches than males – whereas other species are monomorphic. Leucadendron is ecologically diverse, with some species with canopy stored seeds (serotiny) and others with soil stored seeds. These features mean that the Cape Leucadendron is an ideal genus to study the costs of reproduction for the different sexes in plants, and to determine whether vegetative dimorphism could be due to unequal costs. Here we use the unique aspects of the fire-prone Cape environment in which leucadendrons occur to show that the costs of sex must be equal between the sexes. Leucadendron populations are single aged because they only recruit after fires that kill all adults. Therefore, because the sexes have the same lifespans, they must have the same lifetime extent of vegetative versus reproductive allocation. Also, ecologically similar hermaphrodite Proteaceae co-exist with dioecious taxa. To co-occur, dioecious and hermaphrodite taxa must have the same mean post-fire fitness. This implies that dioecious females must have double the reproductive output that a co-occurring hermaphrodite has. This is only possible if the costs of reproduction are the same for the sexes and that the sexes use the same resources for reproduction. Finally, because males and female co-occur, they must be competitively equivalent to maintain natal sex ratios. These three factors suggest male and female allocate equivalently and therefore that vegetative sexual dimorphism is unlikely to be due to differences in allocation.

scholarly journals The evolution of floral biology in basal angiosperms

2010 ◽  
Vol 365 (1539) ◽  
pp. 411-421 ◽  
Author(s):  
Peter K. Endress
Keyword(s):  
Floral Biology ◽  
Secretory Structures ◽  
Basal Angiosperms ◽  
Male And Female ◽  
Male Function ◽  
Female Function ◽  
Male Phase ◽  
Synchronous Dichogamy ◽  
Almost All

In basal angiosperms (including ANITA grade, magnoliids, Choranthaceae, Ceratophyllaceae) almost all bisexual flowers are dichogamous (with male and female functions more or less separated in time), and nearly 100 per cent of those are protogynous (with female function before male function). Movements of floral parts and differential early abscission of stamens in the male phase are variously associated with protogyny. Evolution of synchronous dichogamy based on the day/night rhythm and anthesis lasting 2 days is common. In a few clades in Magnoliales and Laurales heterodichogamy has also evolved. Beetles, flies and thrips are the major pollinators, with various degrees of specialization up to large beetles and special flies in some large-flowered Nymphaeaceae, Magnoliaceae, Annonaceae and Aristolochiaceae. Unusual structural specializations are involved in floral biological adaptations (calyptras, inner staminodes, synandria and food bodies, and secretory structures on tepals, stamens and staminodes). Numerous specializations that are common in monocots and eudicots are absent in basal angiosperms. Several families are poorly known in their floral biology.

scholarly journals Time for a change: patterns of sex expression, health and mortality in a sex-changing tree

2019 ◽  
Vol 124 (3) ◽  
pp. 367-377 ◽  
Author(s):  
Jennifer Blake-Mahmud ◽  
Lena Struwe
Keyword(s):  
Life History ◽  
Sex Determination ◽  
Classification Tree ◽  
Sex Ratios ◽  
Sex Expression ◽  
Life History Trait ◽  
Differential Mortality ◽  
Male And Female ◽  
Female Sex ◽  
Theoretical Predictions

Abstract Background and Aims The ability of individuals to change sex during their lifetime is known as environmental sex determination (ESD). This represents a unique life history trait, allowing plants to allocate resources differentially to male and female functions across lifetimes, potentially maximizing fitness in response to changing environmental or internal cues. In this study, Acer pensylvanicum, a species with an unconfirmed sex determination system, was investigated to see what patterns in sex expression existed across multiple years, if there were sex-based differences in growth and mortality, and whether this species conformed to theoretical predictions that females are larger and in better condition. Methods Patterns of sex expression were documented over 4 years in a phenotypically subdioecious A. pensylvanicum population located in New Jersey, USA, and data on size, mortality, health and growth were collected. A machine-learning algorithm known as a boosted classification tree was used to develop a model to predict the sex of a tree based on its condition, size and previous sex. Results In this study, 54 % of the trees switched sex expression during a 4-year period, with 26 % of those trees switching sex at least twice. Consistently monoecious trees could change relative sex expression by as much as 95 %. Both size and condition were influential in predicting sex, with condition exerting three times more relative influence than size on expressed sex. Contrary to theoretical predictions, the model showed that full female sex expression did not increase with size. Healthy trees were more likely to be male; predicted female sex expression increased with deteriorating health. Growth rate negatively correlated with multiple years of female sex expression. Populations maintained similar male-skewed sex ratios across years and locations and may result from differential mortality: 75 % of dead trees flowered female immediately before death. Conclusions This study shows conclusively that A. pensylvanicum exhibits ESD and that femaleness correlates with decreased health, in contrast to prevailing theory. The mortality findings advance our understanding of puzzling non-equilibrium sex ratios and life history trade-offs resulting from male and female sex expression.

scholarly journals The physiological costs of reproduction in small mammals

2007 ◽  
Vol 363 (1490) ◽  
pp. 375-398 ◽  
Author(s):  
John R Speakman
Keyword(s):  
Life History ◽  
Small Mammals ◽  
Morphological Changes ◽  
Life History Evolution ◽  
Indirect Costs ◽  
Direct Costs ◽  
Costs Of Reproduction ◽  
Dominant Component ◽  
Trade Offs ◽  
Almost All

Life-history trade-offs between components of fitness arise because reproduction entails both gains and costs. Costs of reproduction can be divided into ecological and physiological costs. The latter have been rarely studied yet are probably a dominant component of the effect. A deeper understanding of life-history evolution will only come about once these physiological costs are better understood. Physiological costs may be direct or indirect. Direct costs include the energy and nutrient demands of the reproductive event, and the morphological changes that are necessary to facilitate achieving these demands. Indirect costs may be optional ‘compensatory costs’ whereby the animal chooses to reduce investment in some other aspect of its physiology to maximize the input of resource to reproduction. Such costs may be distinguished from consequential costs that are an inescapable consequence of the reproductive event. In small mammals, the direct costs of reproduction involve increased energy, protein and calcium demands during pregnancy, but most particularly during lactation. Organ remodelling is necessary to achieve the high demands of lactation and involves growth of the alimentary tract and associated organs such as the liver and pancreas. Compensatory indirect costs include reductions in thermogenesis, immune function and physical activity. Obligatory consequential costs include hyperthermia, bone loss, disruption of sleep patterns and oxidative stress. This is unlikely to be a complete list. Our knowledge of these physiological costs is currently at best described as rudimentary. For some, we do not even know whether they are compensatory or obligatory. For almost all of them, we have no idea of exact mechanisms or how these costs translate into fitness trade-offs.

The costs of reproduction in tree swallows (Tachycineta bicolor)

1991 ◽  
Vol 69 (10) ◽  
pp. 2540-2547 ◽  
Author(s):  
Nathaniel T. Wheelwright ◽  
Joanna Leary ◽  
Caragh Fitzgerald
Keyword(s):  
Life History ◽  
Clutch Size ◽  
Brood Size ◽  
Life History Theory ◽  
Tachycineta Bicolor ◽  
Laying Date ◽  
Tree Swallows ◽  
Costs Of Reproduction ◽  
Return Rates ◽  
Trade Offs

We investigated the effect of brood size on nestling growth and survival, parental survival, and future fecundity in tree swallows (Tachycineta bicolor) over a 4-year period (1987–1990) in an effort to understand whether reproductive trade-offs limit clutch size in birds. In addition to examining naturally varying brood sizes in a population on Kent Island, New Brunswick, Canada, we experimentally modified brood sizes, increasing or decreasing the reproductive burdens of females by two offspring. Unlike previous studies, broods of the same females were enlarged or reduced in up to 3 successive years in a search for evidence of cumulative costs of reproduction that might go undetected by a single brood manipulation. Neither observation nor experiment supported the existence of a trade-off between offspring quality and quantity, in contrast with the predictions of life-history theory. Nestling wing length, mass, and tarsus length were unrelated to brood size. Although differences between means were in the direction predicted, few differences were statistically significant, despite large sample sizes. Nestlings from small broods were no more likely to return as breeding adults than nestlings from large broods, but return rates of both groups were very low. Parental return rates were also independent of brood size, and there was no evidence of a negative effect of brood size on future fecundity (laying date, clutch size). Reproductive success, nestling size, and survival did not differ between treatments for females whose broods were manipulated in successive years. Within the range of brood sizes observed in this study, the life-history costs of feeding one or two additional nestlings in tree swallows appear to be slight and cannot explain observed clutch sizes. Costs not measured in this study, such as the production of eggs or postfledging parental care, may be more important in limiting clutch size in birds.

A new species of Hypatima Hübner (Lepidoptera: Gelechiidae) injurious to mango trees in East Africa

1989 ◽  
Vol 79 (3) ◽  
pp. 411-420 ◽  
Author(s):  
K. Sattler ◽  
A. B. Stride
Keyword(s):  
Life History ◽  
New Species ◽  
East Africa ◽  
Female Genitalia ◽  
Field Observations ◽  
Laboratory Studies ◽  
Male And Female ◽  
Extensive Field ◽  
A New Species

AbstractHypatima mangiferae Sattler sp. n. is described from Kenya, where its larva is injurious to commercial mango trees. A description of its life-history, based on extensive field observations and laboratory studies, is also provided. The moth, its male and female genitalia and the damage caused by the larva are illustrated.

Cross-sexual Transfer

2003 ◽  
Author(s):  
Mary Jane West-Eberhard
Keyword(s):  
Sex Determination ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Alternative Phenotypes ◽  
Opposite Sex ◽  
Critical Age ◽  
Sexual Traits ◽  
Discrete Traits ◽  
Dimorphic Species ◽  
Determination Mechanism

Distinctive male and female traits are perhaps the most familiar of all divergent specializations within species. In cross-sexual transfer, discrete traits that are expressed exclusively in one sex in an ancestral species appear in the opposite sex of descendants. An example is the expression of brood care by males in a lineage where ancestral females are the exclusive caretakers of the young, as in some voles (Thomas and Birney, 1979). Despite the prominence of sexual dimorphism and sex reversals in nature, and an early explicit treatment by Darwin, discussed in the next section, cross-sexual transfer is not often recognized as a major factor in the evolution of novelty (but see, on animals, Mayr, 1963, pp. 435-439; Mayr, 1970, p. 254; on plants, Iltis, 1983). When more widely investigated, cross-sexual transfer may prove to rival heterochrony and duplication as an important source of novelties in sexually dimorphic lineages. For this reason, I devote more attention here to cross-sexual transfer than to these other, well-established general patterns of change. The male and female of a sexually dimorphic species may be so different that it is easy to forget that each individual carries most or all of the genes necessary to produce the phenotype of the opposite sex. Sex determination, like caste determination and other switches between alternative phenotypes, depends on only a few genetic loci or, in many species, environmental factors (Bull, 1983). There is considerable flexibility in sex determination and facultative reversal in some taxa. Among fish, for example, there is even a species wherein sex is determined by juvenile size at a critical age (Francis and Barlow, 1993). The sex determination mechanism, whatever its nature, leads to a series of sex-limited responses, often coordinated by hormones and not necessarily all occurring at once. A distinguishing aspect of sexually dimorphic traits in adults is that there is often a close homology between the secondary sexual traits that are differently modified in the two sexes.

A new avocado pest in Central America (Lepidoptera: Tortricidae) with a key to Lepidoptera larvae threatening avocados in California

Zootaxa ◽  
2011 ◽  
Vol 3137 (1) ◽  
pp. 31 ◽  
Author(s):  
TODD M. GILLIGAN ◽  
JOHN W. BROWN ◽  
MARK S. HODDLE
Keyword(s):  
Life History ◽  
New Species ◽  
Central America ◽  
Secondary Structures ◽  
Persea Americana ◽  
Female Genitalia ◽  
Complete List ◽  
Male And Female ◽  
Avocado Fruit ◽  
Potential Pest

Cryptaspasma perseana Gilligan and Brown, new species, is described and illustrated from Mexico and Guatemala. This species is a potential pest of the fruit of cultivated avocado, Persea americana (Lauraceae). Images of adults, male secondary structures, male and female genitalia, eggs, larvae, and pupae are provided. Details of the life history are reviewed. We provide characters to differentiate this pest from the most common avocado fruit pest in the region, Stenoma catenifer (Walsingham) (Elachistidae), and a key to identify Lepidoptera larvae threatening avocado in California. In addition, we provide a complete list of tortricids documented from different avocado varieties worldwide.

scholarly journals Senescence and costs of reproduction in the life history of a small precocial species

2019 ◽  
Vol 9 (12) ◽  
pp. 7069-7079
Author(s):  
Fritz Trillmich ◽  
Edda Geißler ◽  
Anja Guenther
Keyword(s):  
Life History ◽  
Costs Of Reproduction ◽  
History Of

A new species of Stenomicra Coquillett (Diptera: Periscelididae) from the Brazilian Amazon and its life history

Zootaxa ◽  
2018 ◽  
Vol 4407 (4) ◽  
pp. 591
Author(s):  
ELIANE SOLAR GOMES ◽  
ROSALY ALE-ROCHA ◽  
RUTH LEILA FERREIRA KEPPLER
Keyword(s):  
Life History ◽  
New Species ◽  
Urban Forest ◽  
Brazilian Amazon ◽  
Neotropical Region ◽  
Biological Information ◽  
Forest Fragment ◽  
Male And Female ◽  
The City ◽  
A New Species

A new species of Stenomicra is described for the Neotropical Region, from phytotelmata of Araceae at an urban forest fragment in the city of Manaus, state of Amazonas, Brazil. Morphological descriptions of the immatures and the adults (male and female) are provided, together with biological information on the life cycle of the species and its “host” plant. 

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