**1. Introduction**

Life-history traits, known as fitness components due to their predictable monotonic relationship with fitness, are related to the timing and success of development, reproduction, and

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

senescence throughout the life cycle [1]. The environment has appreciable influences on plant life histories and in the life cycle, the timing of life-history traits (e.g., flowering, seed set, seed mass, seed number, seed dormancy intensity [i.e., delayed onset of germination], seed emergence, etc.) are covaried and thus probably coevolved. Examples for the interplay between the environment and life-history traits at ecological and/or evolutionary levels are instantiated as follows.


Some life-history traits may have reciprocal effects with functional traits at late life stages of regeneration. Environmental challenges, mostly to the maternal plant, influence the resources


Notes: (1) In general, species that produce light seeds are more likely to possess some type of seed dormancy [69, 142]. Other correlations were also documented and these inconsistencies may be explained by an incomplete consideration of other covarying factors (e.g., dispersal, fire, and predation) [13] or by phylogenetic constraints [151]. Variation in seed size and dormancy often results from a seed position effect within an inflorescence and within a dispersal unit [35, 50] and this also contributes to uncertainties of their associations. At molecular levels, the parent-of-origin effects on seed traits (e.g., dormancy and size), which are regulated by chromatin remodeling, have been documented for crossing between plants in different ploidy and mutants defective at reproduction [152].

(2) Such correlation remains in the question, as the cited study did not measure whether "the degree of dormancy" was related to persistence. Contrasted with seed release at maturity, canopy seed storage (i.e., serotiny) is reviewed in [153] and we do not extensively discuss canopy-stored seed banks in this chapter. Global warming is expected to reduce seedling emergence for some species [154, 155]. Moreover, the evolution of seed dormancy is favored by high seed persistence in the soil seed bank to alleviate the cost of delayed germination [156]. Both Cohen and Ellner's models suggested that an increase in seed survivorship selects for a low seed germination [88–90]. Soil temperature is the dominant environmental factor controlling the depth of seed dormancy during cycling in imbibed seeds [157]. Climate change engenders long-term exposure to high soil temperatures, which may reduce seed survival, thus selecting for decreased levels of seed dormancy [158]. Taken together, climate change may increase seed numbers in the life cycle and decrease dormancy levels due to increased seed mortality.

(3) Dormancy cycling coupled to seed longevity represents a bet-hedging strategy through persistence in the soil seed bank [159, 160]. As a consequence, seed persistence may be not simply associated with either seed dormancy or longevity. (4) The mother plant has a significant influence over seed traits and instances have been documented for more than 10 decades. Factors such as age of the mother plant, position of the seed in the fruit, inflorescence, or canopy can affect seed properties, often accompanied by a dimorphism either of the seeds themselves or the fruits in which they arise [161].

**Table 1.** A summary of correlations of adaptive traits.

senescence throughout the life cycle [1]. The environment has appreciable influences on plant life histories and in the life cycle, the timing of life-history traits (e.g., flowering, seed set, seed mass, seed number, seed dormancy intensity [i.e., delayed onset of germination], seed emergence, etc.) are covaried and thus probably coevolved. Examples for the interplay between the environment and life-history traits at ecological and/or evolutionary levels are instantiated as

• At a global scale, seed dormancy tends to decrease and seed size to increase toward the

• Life cycles with early flowering, small seeds, deep dormancy, and slow germination are associated with habitats exposed to high temperature, low rainfall, and high radiation [5].

• Lower temperatures with as little as 1°C differences (*T*critical = 15°C) to the maternal plant in

• Under natural conditions, a given plant may produce seeds with different levels of dormancy in association with a particular temperature it has experienced during seed devel-

• Variations in seed dormancy and mass often have a concomitant effect (reviewed by [4])

• Species showing very fast germination behavior have (very) small seeds and little or no endosperm, and there is a clear relationship between the phenomenon of very fast germination and high stress habitats (e.g., arid, saline, or in active floodplains), where seeds can

• There is a positive correlation of relative embryo length with germination speed and negative correlations with the amount of habitat shade, longevity and precipitation [note that

• Climate change is accelerating plant developmental transitions in temperate environments

• Early germination increases seed fecundity due to prolonged vegetative growth and nutri-

• There is a strong relatedness between seed mass and the depth of burial from which seedlings emerge [19, 20] and germination of large seeds is strongly facilitated by temperature

• There exists a negative correlation between seed dormancy and longevity [24] with small

• There are strong correlations between seed mass and dispersal syndromes and their cor-

Some life-history traits may have reciprocal effects with functional traits at late life stages of regeneration. Environmental challenges, mostly to the maternal plant, influence the resources

(Note: warming selects for higher optimal photosynthetic temperatures.)

rapidly exploit temporarily favorable conditions for germination [16].

and advanced flower timing increases dormancy intensities [5, 8, 18].

ent accumulation but may also bring about high seedling mortality [5].

seeds persisting longer in soil seed banks than large seeds [25].

relations hinge on dispersal vectors [26, 27].

fluctuations, ensuring germination after deep burial or in litter layers [21–23].

and are correlated in a negative manner [5, 11–15].

small embryo sizes are typical of primitive taxa] [17].

Arabidopsis, on the contrary, tend to enhance final seed dormancy levels [6–9].

follows.

equator [2–4].

4 Advances in Seed Biology

opment [10].

that are packaged into seeds (seed size) and may be critical for germination and initial seedling growth. For instance, small-seeded species have small plant size (e.g., a positive correlation between seed mass and plant height [28]). Larger plant size, in turn, has higher annual photosynthetic incomes, giving the plant more energy to allocate to seed yield (increased number, heavier mass, or a trade-off between the two in life cycles). Rather, there are studies reporting that seed mass, nature plant height, and leaf mass per unit area have little intercorrelations [29] and that seed dormancy strategy is largely independent of vegetative functional traits and range characteristics [30]. Those inconsistent reports supply us with clues to studying the interaction between adaptive traits in a broader scope (e.g., controlling for phylogeny, more species from different taxa, and/or more traits at different stages of life cycles).

**Figure 1.** Relatedness among life-history and functional traits and the impact of climate change on the variation (and evolution) of these traits. Note: Lines give interactions between traits (boxes) in a positive or negative manner and the change of direction (↑ or ↓) depends on another trait(s). The arrow linking two traits prompts which trait affects the other. Sun and water drop symbols stand for temperature and rainfall, respectively.


Note: When maternal plants are deprived of resources, seed provisioning may be reduced (e.g., [145]), maintained or even increased (e.g., [167, 168, 174]), as trade-offs may exist between increased seed provisioning and decreased persistence in the soil seed bank [145, 167, 174] and thus the benefits may depend on a specific ecological setting.

Progressive global warming leads to widespread shifts toward earlier initiation of flowering in many plant populations, which contributes to an increase in the length of the flowering season in regions where flowering is temperaturedependent [175–177]. Note that longer growing seasons select for later flowering and thus warming and growing season may comprise a trade-off. As the detection of the relatedness between flowering locus and ambient temperature [72, 178], the flowering time diversity is associated with *cis*-regulatory variation [179] and further, flowering time loci restrict potential range size and niche breadth [180].

**Table 2.** Examples for the effect of different parental environments on offspring adaptive traits.

Last, we provided a summary of interplay patterns between traits (life-history, functional traits, and a combination thereof) as influenced by climatic factors in **Table 1** and **Figure 1**. We also listed examples on adaptive traits with transgenerational plasticity as responses to altered maternal environmental conditions in **Table 2**.
