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Observation: For plant species with separate sexes, the average population sex ratio is female biased in mosses and liverworts, male biased in trees and shrubs, and unbiased in short-lived herbs. Key assumption: When fertilization occurs, female investment in reproduction greatly outweighs male investment. Questions: Can we explain the general pattern in population sex ratios from primary sex ratios in seeds or spores? What does genomic conflict theory predict for sex ratios of angiosperms and bryophytes? Are there other explanatory factors? Data studied: Literature review of variation in sex ratio found in seeds and spores and of male and female performance. Conclusion: Primary sex ratios were often variable, suggesting genomic conflict involving both cytoplasmic factors and sex-linked drive. Even though theory predicts some differences, primary sex ratios of angiosperms and bryophytes were remarkably similar. Males sometimes perform worse than females in the pre-reproductive phase and this may result in a female bias before reproduction occurs. In the reproductive stage, females invest more than males and may suffer greater mortality. The sex ratio of a cohort may then slowly change from female to male bias. This might explain the different population sex ratios of short-lived (herbs) and long-lived angiosperms (trees). In bryophytes, low fertilization rates, reducing female allocation to reproduction, could shift the balance towards consistent female bias in their populations.

Questions: Is there evidence of recent altitudinal range shifts in a hyper-arid Middle Eastern desert mountain flora? How do the directions of shift for upper and lower altitudinal range limits of plants vary? Location: Hyper-arid mountain desert, St Katherine Protectorate, South Sinai, Egypt. Method: We tested for shifts in both upper and lower altitudinal range limits by comparing a 1970s dataset of recorded species’ limits with recent surveys using altitudinal transects across 36 sites. Altitudinal limits between 63 paired upper-limit and 22 paired lower-limit values from the 1970s and 2014 were compared using paired t-tests; binomial tests were used to indicate the dominant direction of change. The upper and lower limits of 22 species were considered together to allow assessment of overall altitudinal range-size changes. In order to avoid the potential effect of yearly environmental fluctuations on the distributions of annual species, subsets of upper and lower limit shifts were taken for perennials, and trees and shrubs. Results: Our results show significant overall upslope shifts in mean upper altitudinal limits and significant overall downslope shifts in mean lower altitudinal limits. A majority of assessed species expanded their altitudinal ranges, but the responses of individual species varied. Since perennial herbs/graminoids, and trees and shrubs, show strong patterns of change, we suggest there has been a long-term shift in altitudinal range in South Sinai’s mountain flora. Greater research effort needs to be focussed upon the drivers of range-shift responses in arid regions.

Questions: Is there evidence of recent altitudinal range shifts in a hyper-arid Middle Eastern desert mountain flora? How do the directions of shift for upper and lower altitudinal range limits of plants vary? Location: Hyper-arid mountain desert, St Katherine Protectorate, South Sinai, Egypt. Method: We tested for shifts in both upper and lower altitudinal range limits by comparing a 1970s dataset of recorded species’ limits with recent surveys using altitudinal transects across 36 sites. Altitudinal limits between 63 paired upper-limit and 22 paired lower-limit values from the 1970s and 2014 were compared using paired t-tests; binomial tests were used to indicate the dominant direction of change. The upper and lower limits of 22 species were considered together to allow assessment of overall altitudinal range-size changes. In order to avoid the potential effect of yearly environmental fluctuations on the distributions of annual species, subsets of upper and lower limit shifts were taken for perennials, and trees and shrubs. Results: Our results show significant overall upslope shifts in mean upper altitudinal limits and significant overall downslope shifts in mean lower altitudinal limits. A majority of assessed species expanded their altitudinal ranges, but the responses of individual species varied. Since perennial herbs/graminoids, and trees and shrubs, show strong patterns of change, we suggest there has been a long-term shift in altitudinal range in South Sinai’s mountain flora. Greater research effort needs to be focussed upon the drivers of range-shift responses in arid regions.

Questions: Is there evidence of recent altitudinal range shifts in a hyper-arid Middle Eastern desert mountain flora? How do the directions of shift for upper and lower altitudinal range limits of plants vary? Location: Hyper-arid mountain desert, St Katherine Protectorate, South Sinai, Egypt. Method: We tested for shifts in both upper and lower altitudinal range limits by comparing a 1970s dataset of recorded species’ limits with recent surveys using altitudinal transects across 36 sites. Altitudinal limits between 63 paired upper-limit and 22 paired lower-limit values from the 1970s and 2014 were compared using paired t-tests; binomial tests were used to indicate the dominant direction of change. The upper and lower limits of 22 species were considered together to allow assessment of overall altitudinal range-size changes. In order to avoid the potential effect of yearly environmental fluctuations on the distributions of annual species, subsets of upper and lower limit shifts were taken for perennials, and trees and shrubs. Results: Our results show significant overall upslope shifts in mean upper altitudinal limits and significant overall downslope shifts in mean lower altitudinal limits. A majority of assessed species expanded their altitudinal ranges, but the responses of individual species varied. Since perennial herbs/graminoids, and trees and shrubs, show strong patterns of change, we suggest there has been a long-term shift in altitudinal range in South Sinai’s mountain flora. Greater research effort needs to be focussed upon the drivers of range-shift responses in arid regions.

Questions: Is there evidence of recent altitudinal range shifts in a hyper-arid Middle Eastern desert mountain flora? How do the directions of shift for upper and lower altitudinal range limits of plants vary? Location: Hyper-arid mountain desert, St Katherine Protectorate, South Sinai, Egypt. Method: We tested for shifts in both upper and lower altitudinal range limits by comparing a 1970s dataset of recorded species’ limits with recent surveys using altitudinal transects across 36 sites. Altitudinal limits between 63 paired upper-limit and 22 paired lower-limit values from the 1970s and 2014 were compared using paired t-tests; binomial tests were used to indicate the dominant direction of change. The upper and lower limits of 22 species were considered together to allow assessment of overall altitudinal range-size changes. In order to avoid the potential effect of yearly environmental fluctuations on the distributions of annual species, subsets of upper and lower limit shifts were taken for perennials, and trees and shrubs. Results: Our results show significant overall upslope shifts in mean upper altitudinal limits and significant overall downslope shifts in mean lower altitudinal limits. A majority of assessed species expanded their altitudinal ranges, but the responses of individual species varied. Since perennial herbs/graminoids, and trees and shrubs, show strong patterns of change, we suggest there has been a long-term shift in altitudinal range in South Sinai’s mountain flora. Greater research effort needs to be focussed upon the drivers of range-shift responses in arid regions.